**Preheat Oven:** Preheat your oven to 375°F (190°C). Grease a bundt pan or baking dish with non-stick cooking spray or butter.
**Prepare Dough:** Cut each biscuit into quarters.
**Combine Ingredients:** In a large mixing bowl, toss the biscuit pieces with mozzarella cheese, mini pepperoni slices, and Parmesan cheese.
**Make Garlic Butter:** In a small bowl, mix melted butter with Italian seasoning, garlic powder, and red pepper flakes (if using).
**Layer in Pan:** Place half of the biscuit mixture into the prepared pan. Drizzle with half of the garlic butter mixture. Repeat with the remaining biscuit mixture and garlic butter.
**Bake:** Bake for 30-35 minutes, or until the top is golden brown and the bread is cooked through. If the top browns too quickly, cover it loosely with foil.
**Cool and Serve:** Let the monkey bread cool in the pan for 5-10 minutes, then carefully invert it onto a serving plate. Serve warm with marinara sauce for dipping.