Preheat oven to 400°F.
Line baking tray with foil.
Place muffin halves onto the prepared baking tray.
Spoon 2 tablespoons crushed tomatoes on each muffin half.
Top with chopped peppers or zucchini and onions as desired.
Sprinkle each pizza with approximately 2 tablespoons shredded cheese.
Place the baking tray in the oven and bake for 15 minutes.
Remove from oven and let cool.