diff --git a/EESSI-extend-2023.06-easybuild.eb b/EESSI-extend-2023.06-easybuild.eb
new file mode 100644
index 0000000000..76e96766f9
--- /dev/null
+++ b/EESSI-extend-2023.06-easybuild.eb
@@ -0,0 +1,167 @@
+easyblock = 'Bundle'
+
+name = 'EESSI-extend'
+version = '2023.06'
+# May have different ways to extend EESSI in future (manually, other tools,...)
+versionsuffix = '-easybuild'
+
+homepage = 'https://eessi.io/docs/'
+
+description = """
+ The goal of the European Environment for Scientific Software Installations
+ (EESSI, pronounced as "easy") is to build a common stack of scientific
+ software installations for HPC systems and beyond, including laptops,
+ personal workstations and cloud infrastructure.
+
+ This module allows you to extend EESSI using the same configuration for
+ EasyBuild as EESSI itself uses. A number of environment variables control the
+ behaviour of the module:
+ - EESSI_USER_INSTALL can be set to a location to install modules for use by
+   the user only. The location must already exist on the filesystem.
+ - EESSI_PROJECT_INSTALL can be set to a location to install modules for use by
+   a project. The location must already exist on the filesystem and you should
+   ensure that the location has the correct Linux group and the SGID permission
+   is set on that directory (`chmod g+s $EESSI_PROJECT_INSTALL`) so that all
+   members of the group have permission to read and write installations.
+ - EESSI_SITE_INSTALL is either defined or not and cannot be used with another
+   environment variable. A site installation is done in a defined location and
+   any installations there are (by default) world readable.
+ - EESSI_CVMFS_INSTALL is either defined or not and cannot be used with another
+   environment variable. A CVMFS installation targets a defined location which
+   will be ingested into CVMFS and is only useful for CVMFS administrators.
+ - If none of the environment variables above are defined, an EESSI_USER_INSTALL
+   is assumed with a value of $HOME/EESSI
+ If both EESSI_USER_INSTALL and EESSI_PROJECT_INSTALL are defined, both sets of
+ installations are exposed, but new installations are created as user
+ installations.
+"""
+
+toolchain = SYSTEM
+
+# All the dependencies we filter in EESSI
+local_deps_to_filter = "Autoconf,Automake,Autotools,binutils,bzip2,DBus,flex,gettext,gperf,help2man,intltool,libreadline,libtool,M4,makeinfo,ncurses,util-linux,XZ,zlib"
+local_arch_specific_deps_to_filter = {'aarch64': ',yasm', 'x86_64': ''}
+local_deps_to_filter += local_arch_specific_deps_to_filter[ARCH]
+
+# Set the universal EasyBuild variables
+modextravars = {
+    'EASYBUILD_FILTER_DEPS': local_deps_to_filter,
+    'EASYBUILD_IGNORE_OSDEPS': '1',
+    'EASYBUILD_DEBUG': '1',
+    'EASYBUILD_TRACE': '1',
+    'EASYBUILD_ZIP_LOGS': 'bzip2',
+    'EASYBUILD_RPATH': '1',
+    'EASYBUILD_FILTER_ENV_VARS': 'LD_LIBRARY_PATH',
+    'EASYBUILD_READ_ONLY_INSTALLDIR': '1',
+    'EASYBUILD_MODULE_EXTENSIONS': '1',
+    'EASYBUILD_EXPERIMENTAL': '1',
+}
+
+# Need a few other variables, but they are more dynamic
+# EASYBUILD_SYSROOT=${EPREFIX}
+# EASYBUILD_PREFIX=${WORKDIR}/easybuild
+# EASYBUILD_HOOKS=${EESSI_PREFIX}/init/easybuild/eb_hooks.py
+# EASYBUILD_INSTALLPATH=${EESSI_PREFIX}/software/${EESSI_OS_TYPE}/${EESSI_SOFTWARE_SUBDIR}
+# EASYBUILD_SOURCEPATH=${WORKDIR}/easybuild/sources:${EESSI_SOURCEPATH}
+#
+# And also some optional ones based on the kind of installation
+# EASYBUILD_SET_GID_BIT
+# EASYBUILD_GROUP_WRITABLE_INSTALLDIR
+# EASYBUILD_UMASK
+# EASYBUILD_STICKY_BIT
+modluafooter = """
+if (mode() == "load") then
+  -- Use a working directory for temporary build files
+  if (os.getenv("WORKING_DIR") == nil) then
+    LmodMessage("-- Using /tmp/$USER as a temporary working directory for installations, you can override this by setting the environment variable WORKING_DIR and reloading the module (e.g., /dev/shm is a common option)")
+  end
+end
+working_dir = os.getenv("WORKING_DIR") or pathJoin("/tmp", os.getenv("USER"))
+-- Gather the EPREFIX to use as a sysroot
+sysroot = os.getenv("EESSI_EPREFIX")
+-- Use an installation prefix that we _should_ have write access to
+if (os.getenv("EESSI_CVMFS_INSTALL") ~= nil) then
+  -- Make sure no other EESSI install environment variables are set
+  if ((os.getenv("EESSI_SITE_INSTALL") ~= nil) or (os.getenv("EESSI_PROJECT_INSTALL") ~= nil) or (os.getenv("EESSI_USER_INSTALL") ~= nil)) then
+    LmodError("You cannot use EESSI_CVMFS_INSTALL in combination with any other EESSI_*_INSTALL environment variables")
+  end
+  eessi_cvmfs_install = true
+  easybuild_installpath = os.getenv("EESSI_SOFTWARE_PATH")
+elseif (os.getenv("EESSI_SITE_INSTALL") ~= nil) then
+  -- Make sure no other EESSI install environment variables are set
+  if ((os.getenv("EESSI_PROJECT_INSTALL") ~= nil) or (os.getenv("EESSI_USER_INSTALL") ~= nil)) then
+    LmodError("You cannot use EESSI_SITE_INSTALL in combination with any other EESSI_*_INSTALL environment variables")
+  end
+  easybuild_installpath = string.gsub(os.getenv("EESSI_SOFTWARE_PATH"), 'versions', 'host_injections')
+else
+  -- Deal with user and project installs
+  project_install = os.getenv("EESSI_PROJECT_INSTALL")
+  project_modulepath = nil
+  if (project_install ~= nil) then
+    -- Check the folder exists
+    if not isDir(project_install) then
+      LmodError("The location of EESSI_PROJECT_INSTALL (" .. project_install .. ") does not exist or is not a folder")
+    end
+    if (mode() == "load") then
+      LmodMessage("Configuring for use of EESSI_PROJECT_INSTALL under " .. project_install)
+    end
+    easybuild_installpath = string.gsub(os.getenv("EESSI_SOFTWARE_PATH"), os.getenv("EESSI_CVMFS_REPO"), project_install)
+    project_modulepath = pathJoin(easybuild_installpath, 'modules', 'all')
+  end
+  user_install = os.getenv("EESSI_USER_INSTALL")
+  user_modulepath = nil
+  if (user_install ~= nil) then
+    -- Check the folder exists
+    if not isDir(user_install) then
+      LmodError("The location of EESSI_USER_INSTALL (" .. user_install .. ") does not exist or is not a folder")
+    end
+  elseif (user_install == nil) and (project_install == nil) then
+    -- No need to check for existence when we use a HOME subdir
+    user_install = pathJoin(os.getenv("HOME"), "eessi")
+  end
+  if (user_install ~= nil) then
+    if (mode() == "load") then
+      LmodMessage("Configuring for use of EESSI_USER_INSTALL under " .. user_install)
+    end
+    easybuild_installpath = string.gsub(os.getenv("EESSI_SOFTWARE_PATH"), os.getenv("EESSI_CVMFS_REPO"), user_install)
+    user_modulepath = pathJoin(easybuild_installpath, 'modules', 'all')
+  end
+end
+if (mode() == "load") then
+  LmodMessage("-- To create installations for EESSI, you _must_ have write permissions to " .. easybuild_installpath)
+  -- Advise them to reuse sources
+  if (os.getenv("EASYBUILD_SOURCEPATH") == nil) then
+    LmodMessage("-- You may wish to configure a sources directory for EasyBuild (for example, via setting the environment variable EASYBUILD_SOURCEPATH) to allow you to reuse existing sources for packages.")
+  end
+end
+-- Set the relevant universal environment variables for EasyBuild
+setenv ("EASYBUILD_SYSROOT", sysroot)
+setenv ("EASYBUILD_PREFIX", pathJoin(working_dir, "easybuild"))
+setenv ("EASYBUILD_INSTALLPATH", easybuild_installpath)
+setenv ("EASYBUILD_HOOKS", pathJoin(os.getenv("EESSI_PREFIX"), "init", "easybuild", "eb_hooks.py"))
+setenv ("EASYBUILD_UMASK", "002")
+
+-- Set all related environment variables if we have project or user installations (including extending MODULEPATH)
+if (user_modulepath ~= nil) then
+  -- Use a more restrictive umask for this case
+  setenv ("EASYBUILD_UMASK", "022")
+  setenv ("EASYBUILD_STICKY_BIT", "1")
+  -- configure MODULEPATH
+  if (project_modulepath ~= nil) then
+    prepend_path("MODULEPATH", project_modulepath)
+  end
+  prepend_path("MODULEPATH", user_modulepath)
+elseif (project_modulepath ~= nil) then
+  setenv ("EASYBUILD_SET_GID_BIT", "1")
+  setenv ("EASYBUILD_GROUP_WRITABLE_INSTALLDIR", "1")
+  setenv ("EASYBUILD_STICKY_BIT", "0")
+  -- configure MODULEPATH
+  prepend_path("MODULEPATH", project_modulepath)
+end
+-- Make sure EasyBuild itself is loaded
+if not ( isloaded("EasyBuild") ) then
+    load("EasyBuild")
+end
+"""
+
+moduleclass = 'devel'
diff --git a/create_tarball.sh b/create_tarball.sh
index 2d77acfc43..0a7669f73f 100755
--- a/create_tarball.sh
+++ b/create_tarball.sh
@@ -28,7 +28,7 @@ fi
 
 overlay_upper_dir="${eessi_tmpdir}/overlay-upper"
 
-software_dir_overlay="${overlay_upper_dir}/versions/${eessi_version}/software/${os}/${cpu_arch_subdir}"
+software_dir_overlay="${overlay_upper_dir}/versions/${eessi_version}"
 if [ ! -d ${software_dir_overlay} ]; then
     echo "Software directory overlay ${software_dir_overlay} does not exist?!" >&2
     exit 3
diff --git a/easystacks/software.eessi.io/2023.06/eessi-2023.06-eb-4.9.1-001-system.yml b/easystacks/software.eessi.io/2023.06/eessi-2023.06-eb-4.9.1-001-system.yml
index c5a08b5209..46ac979719 100644
--- a/easystacks/software.eessi.io/2023.06/eessi-2023.06-eb-4.9.1-001-system.yml
+++ b/easystacks/software.eessi.io/2023.06/eessi-2023.06-eb-4.9.1-001-system.yml
@@ -2,3 +2,4 @@ easyconfigs:
   - EasyBuild-4.9.1.eb:
       options:
         from-pr: 20299
+  - EESSI-extend-2023.06-easybuild.eb
diff --git a/init/Magic_Castle/bash b/init/Magic_Castle/bash
index dbe1772d3a..bf625e7e7b 100644
--- a/init/Magic_Castle/bash
+++ b/init/Magic_Castle/bash
@@ -10,7 +10,7 @@ source $(dirname "$BASH_SOURCE")/../eessi_environment_variables
 
 # Provide a clean MODULEPATH
 export MODULEPATH_ROOT=$EESSI_MODULEPATH
-export MODULEPATH=$EESSI_MODULEPATH
+export MODULEPATH=$EESSI_SITE_MODULEPATH:$EESSI_MODULEPATH
 
 # Extensions are too many, let's not print them by default (requires Lmod 8.4.12)
 export LMOD_AVAIL_EXTENSIONS=no
diff --git a/init/bash b/init/bash
index 0029f91454..93471e075e 100644
--- a/init/bash
+++ b/init/bash
@@ -26,6 +26,8 @@ if [ $? -eq 0 ]; then
     # prepend location of modules for EESSI software stack to $MODULEPATH
     show_msg "Prepending $EESSI_MODULEPATH to \$MODULEPATH..."
     module use $EESSI_MODULEPATH
+    show_msg "Prepending site path $EESSI_SITE_MODULEPATH to \$MODULEPATH..."
+    module use $EESSI_SITE_MODULEPATH
 
     #show_msg ""
     #show_msg "*** Known problems in the ${EESSI_VERSION} software stack ***"
diff --git a/init/eessi_environment_variables b/init/eessi_environment_variables
index 5450b2bfb4..dbf01cc9e4 100644
--- a/init/eessi_environment_variables
+++ b/init/eessi_environment_variables
@@ -89,6 +89,8 @@ if [ -d $EESSI_PREFIX ]; then
           if [ -d $EESSI_MODULEPATH ]; then
             export EESSI_MODULEPATH=$EESSI_MODULEPATH
             show_msg "Using ${EESSI_MODULEPATH} as the directory to be added to MODULEPATH."
+            export EESSI_SITE_MODULEPATH=${EESSI_MODULEPATH/versions/host_injections}
+            show_msg "Using ${EESSI_SITE_MODULEPATH} as the site extension directory to be added to MODULEPATH."
           else
             error "EESSI module path at $EESSI_MODULEPATH not found!"
             false
diff --git a/install_scripts.sh b/install_scripts.sh
index 508735975c..17f0b81008 100755
--- a/install_scripts.sh
+++ b/install_scripts.sh
@@ -113,3 +113,9 @@ nvidia_files=(
     install_cuda_host_injections.sh link_nvidia_host_libraries.sh
 )
 copy_files_by_list ${TOPDIR}/scripts/gpu_support/nvidia ${INSTALL_PREFIX}/scripts/gpu_support/nvidia "${nvidia_files[@]}"
+
+# Copy over EasyBuild hooks file used for installations
+hook_files=(
+    eb_hooks.py
+)
+copy_files_by_list ${TOPDIR} ${INSTALL_PREFIX}/init/easybuild "${hook_files[@]}"