Spread cream cheese onto a microwave-safe pie plate or into the bottom of a small microwave-safe baking dish (you can have the kids use their fingers to press the cream cheese around the bottom of the dish).
Cover with marinara sauce and top with pepperoni (if desired), bell pepper, and mozzarella cheese. Sprinkle with Parmesan cheese and Italian seasoning. Microwave on high for 1-2 minutes, or until heated through, bubbling, and cheese is melted.