diff --git a/.ci_support/migrations/libabseil20240722_grpc165_libprotobuf5275.yaml b/.ci_support/migrations/libabseil20240722_grpc165_libprotobuf5275.yaml
deleted file mode 100644
index 85540a1f..00000000
--- a/.ci_support/migrations/libabseil20240722_grpc165_libprotobuf5275.yaml
+++ /dev/null
@@ -1,18 +0,0 @@
-__migrator:
-  build_number: 1
-  commit_message: Rebuild for libabseil 20240722, libgrp 1.65 & libprotobuf 5.27.5
-  kind: version
-  migration_number: 1
-  exclude:
-    - abseil-cpp
-    - grpc-cpp
-    - libprotobuf
-    - protobuf
-    - re2
-libabseil:
-- 20240722
-libgrpc:
-- "1.65"
-libprotobuf:
-- 5.27.5
-migrator_ts: 1727040240.8650293
diff --git a/.scripts/build_steps.sh b/.scripts/build_steps.sh
index 12647a5e..827a29fb 100755
--- a/.scripts/build_steps.sh
+++ b/.scripts/build_steps.sh
@@ -31,13 +31,13 @@ pkgs_dirs:
 solver: libmamba
 
 CONDARC
+mv /opt/conda/conda-meta/history /opt/conda/conda-meta/history.$(date +%Y-%m-%d-%H-%M-%S)
+echo > /opt/conda/conda-meta/history
+micromamba install --root-prefix ~/.conda --prefix /opt/conda \
+    --yes --override-channels --channel conda-forge --strict-channel-priority \
+    pip  python=3.12 conda-build conda-forge-ci-setup=4 "conda-build>=24.1"
 export CONDA_LIBMAMBA_SOLVER_NO_CHANNELS_FROM_INSTALLED=1
 
-mamba install --update-specs --yes --quiet --channel conda-forge --strict-channel-priority \
-    pip mamba conda-build conda-forge-ci-setup=4 "conda-build>=24.1"
-mamba update --update-specs --yes --quiet --channel conda-forge --strict-channel-priority \
-    pip mamba conda-build conda-forge-ci-setup=4 "conda-build>=24.1"
-
 # set up the condarc
 setup_conda_rc "${FEEDSTOCK_ROOT}" "${RECIPE_ROOT}" "${CONFIG_FILE}"
 
diff --git a/.scripts/run_osx_build.sh b/.scripts/run_osx_build.sh
index dfef5ae1..7f948c41 100755
--- a/.scripts/run_osx_build.sh
+++ b/.scripts/run_osx_build.sh
@@ -7,28 +7,39 @@ source .scripts/logging_utils.sh
 set -xe
 
 MINIFORGE_HOME=${MINIFORGE_HOME:-${HOME}/miniforge3}
+MINIFORGE_HOME=${MINIFORGE_HOME%/} # remove trailing slash
 
-( startgroup "Installing a fresh version of Miniforge" ) 2> /dev/null
-
-MINIFORGE_URL="https://github.com/conda-forge/miniforge/releases/latest/download"
-MINIFORGE_FILE="Miniforge3-MacOSX-$(uname -m).sh"
-curl -L -O "${MINIFORGE_URL}/${MINIFORGE_FILE}"
-rm -rf ${MINIFORGE_HOME}
-bash $MINIFORGE_FILE -b -p ${MINIFORGE_HOME}
-
-( endgroup "Installing a fresh version of Miniforge" ) 2> /dev/null
+( startgroup "Provisioning base env with micromamba" ) 2> /dev/null
+MICROMAMBA_VERSION="1.5.10-0"
+if [[ "$(uname -m)" == "arm64" ]]; then
+  osx_arch="osx-arm64"
+else
+  osx_arch="osx-64"
+fi
+MICROMAMBA_URL="https://github.com/mamba-org/micromamba-releases/releases/download/${MICROMAMBA_VERSION}/micromamba-${osx_arch}"
+MAMBA_ROOT_PREFIX="${MINIFORGE_HOME}-micromamba-$(date +%s)"
+echo "Downloading micromamba ${MICROMAMBA_VERSION}"
+micromamba_exe="$(mktemp -d)/micromamba"
+curl -L -o "${micromamba_exe}" "${MICROMAMBA_URL}"
+chmod +x "${micromamba_exe}"
+echo "Creating environment"
+"${micromamba_exe}" create --yes --root-prefix "${MAMBA_ROOT_PREFIX}" --prefix "${MINIFORGE_HOME}" \
+  --channel conda-forge \
+  pip python=3.12 conda-build conda-forge-ci-setup=4 "conda-build>=24.1"
+echo "Moving pkgs cache from ${MAMBA_ROOT_PREFIX} to ${MINIFORGE_HOME}"
+mv "${MAMBA_ROOT_PREFIX}/pkgs" "${MINIFORGE_HOME}"
+echo "Cleaning up micromamba"
+rm -rf "${MAMBA_ROOT_PREFIX}" "${micromamba_exe}" || true
+( endgroup "Provisioning base env with micromamba" ) 2> /dev/null
 
 ( startgroup "Configuring conda" ) 2> /dev/null
 
-source ${MINIFORGE_HOME}/etc/profile.d/conda.sh
+source "${MINIFORGE_HOME}/etc/profile.d/conda.sh"
 conda activate base
 export CONDA_SOLVER="libmamba"
 export CONDA_LIBMAMBA_SOLVER_NO_CHANNELS_FROM_INSTALLED=1
 
-mamba install --update-specs --quiet --yes --channel conda-forge --strict-channel-priority \
-    pip mamba conda-build conda-forge-ci-setup=4 "conda-build>=24.1"
-mamba update --update-specs --yes --quiet --channel conda-forge --strict-channel-priority \
-    pip mamba conda-build conda-forge-ci-setup=4 "conda-build>=24.1"
+