Preheat the oven to 400˚F and line a baking sheet with parchment.
Heat the butter in a skillet over medium-high heat and add the cauliflower.
Season with salt and pepper, then cover and cook for 15 minutes, stirring occasionally, until very tender.
Spoon the cauliflower into a bowl and stir in ½ cup mozzarella along with the parmesan and garlic powder.
Stir in the egg white and Italian seasoning, then pour onto the baking sheet.
Shape the dough into a circle about ½-inch thick, then bake for 15 minutes.
Top with tomato sauce, along with the remaining mozzarella and pepperoni, bacon, and ham.
Broil until the cheese is browned, then slice to serve.
