Preheat your oven to 375°F (190°C). Grease a muffin tin with non-stick spray or line with muffin liners.
In a large bowl, whisk together the flour, baking powder, salt, and sugar.
In another bowl, combine the milk, vegetable oil, and egg. Mix well.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Fold in the mozzarella cheese, cooked sausage, pepperoni, oregano, and garlic powder until evenly distributed.
Spoon the batter into the prepared muffin tin, filling each cup about 2/3 full.
Top each muffin with a spoonful of marinara sauce and a sprinkle of Parmesan cheese.
Bake for 20-25 minutes, or until the muffins are golden brown and a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack. Serve warm.
