The Central American pyramids are built this way, rubble covered with a facing. You want to enlarge it, more rubble and more facing.
The Central American pyramids are for the most part nested — the first pyramid got built, then some calendrical cycle ended and a new one was begun, which when finished covered the previous one, and so on. There’s a rubble core in some that have insides that are known (obviously it would be expensive to look inside each one), but they aren’t nearly as large as the Giza pyramids, and are quite steep, which transfers the burden to the ground via the stone.