Preheat the oven: Set your oven to 400°F (200°C).
Lightly grease two oven-safe bowls or small baking dishes.
Sauté the veggies: Heat oil in a skillet over medium heat. Add onion, mushrooms, and bell pepper. Cook 4–5 minutes until softened and lightly browned.
Stir in garlic and cook 30 seconds more. Season with a pinch of salt and pepper.
Warm the protein: Add the cooked sausage to the skillet and toss to combine. If using ground beef instead, make sure it’s fully cooked and drained before adding.
Season the base: Sprinkle in oregano, Italian seasoning, and red pepper flakes if using.
Taste and adjust salt and pepper.
Layer the bowls: Divide half the marinara between the bowls. Top with half the mozzarella. Spoon the sausage-veg mixture over the cheese.
Add pepperoni and any optional extras. Dollop on the remaining marinara, then finish with the rest of the mozzarella and the Parmesan.
Bake until bubbly: Place bowls on a sheet pan and bake 10–12 minutes, until the cheese is melted and starting to brown at the edges.
Broil for a golden top (optional): Broil 1–2 minutes to get that pizzeria-style browned cheese. Watch closely to avoid burning.
Finish and serve: Let cool for 3–5 minutes.
Garnish with fresh basil or parsley. Serve hot.