Prep the ingredients: Dice veggies into small, bite-size pieces. If using sausage, slice or crumble. Shred the cheese if not pre-shredded.
Cook the protein: Heat a large skillet over medium.
Add a light drizzle of olive oil. Brown ground turkey or chicken, breaking it up with a spoon, until cooked through. Season with salt, pepper, and a pinch of Italian seasoning.
If using pre-cooked chicken, simply warm it through.
Sauté the veggies: In the same skillet, add onions and peppers first. Cook 3–4 minutes until just softened. Add mushrooms and garlic.
Cook another 2–3 minutes. Toss in spinach at the end until wilted. Season lightly.
Warm the sauce: Pour marinara or pizza sauce into the skillet with the cooked protein and veggies.
Stir to combine. Simmer 2–3 minutes. If you want a creamier, higher-protein sauce, whisk in 1/4–1/3 cup Greek yogurt off the heat, then return to low heat briefly.
Do not boil after adding yogurt.
Assemble the bowls: Divide the saucy mixture among 4 oven-safe bowls or ramekins. Top each with mozzarella, a sprinkle of Parmesan, and a few slices of pepperoni if using. Add red pepper flakes if you like heat.
Melt and brown the cheese: Place bowls on a baking sheet.
Broil on the top rack for 2–5 minutes, watching closely, until the cheese is melted, bubbling, and lightly golden. Alternatively, cover and microwave each bowl 45–90 seconds until the cheese melts.
Finish and serve: Let the bowls rest 2 minutes. Garnish with extra Italian seasoning or fresh basil.
Taste and adjust salt and pepper if needed.