Simmer marinara sauce with some healthy dashes of garlic powder and Italian seasoning for about 30-60 minutes to develop flavor if you have time. If you don't, just use the marinara straight from the jar, adding seasoning.
Lay pepperoni slices on a double layer of paper towels and cover with another towel. Microwave for 20 seconds and blot well with towels to absorb grease.
Boil pasta 2 minutes and drain.
Put a thin layer of sauce in the bottom of prepared baking dish and top with a layer of ravioli. Top with pepperoni slices and sprinkle with cheese. Repeat layers. Refrigerate up to 24 hours. Bake covered at 325 for 30 minutes. Uncover and continue baking 15-30 minutes until hot and bubbly.
Serves 6