Preheat the oven to 350 degrees F. Spray a 9-inch x 13-inch baking dish with non-stick cooking spray and set aside.
Place a large skillet over medium heat. Add the Italian sausage and cook for 8-10 minutes until it's no longer pink and is nicely browned. Transfer to a paper towel-lined bowl to drain. (This can be done ahead of time, and the cooked sausage can be kept in the fridge until you're ready to use it later.)
While the sausage cooks, take the biscuits out of the can and separate them into individual biscuits. Then cut each biscuit into quarters. Place the biscuit pieces in an even layer in the prepared baking dish.
Spread the pizza sauce over the biscuits and then sprinkle with 1 1/2 cups of mozzarella. Place the pepperoni slices, cooked Italian sausage, bell pepper, onions, mushrooms, and black olives over the cheese. Then sprinkle the remaining 1/2 cup cheese over the top.
Bake for 25-30 minutes or until the biscuits are cooked through and the cheese is melted.
Remove from the oven and let stand for 5 minutes before cutting into portions. Serve warm.
Notes
I use two of the 16.3-ounce Pilsbury Grands! Big Biscuits canisters. If you want to use the smaller, cheaper biscuits, just be sure to buy 5 canisters to have around 35 ounces of biscuits.