Pre-heat oven to 350 degrees.
Heat 1 tablespoon olive oil in a large frying pan, until shimmering. Add the onion and cook for 5 minutes, until translucent.
Stir in minced garlic. Cook for about 30 seconds, or until fragrant.
Stir in diced tomatoes and Italian seasoning. Cook until slightly thickened, about 15 minutes. Remove from heat and set aside.
Add 1 teaspoon olive oil to each well of a cupcake tin.
Roll out pizza dough until about 1/4 inch thick. Using a biscuit cutter slightly larger than the opening of your cupcake pan, cut out rounds of dough and push them into the cupcake pans. (If you don’t have a biscuit cutter, a large cup or small bowl would work too!)
Add a heaping tablespoon of the tomato sauce to each pizza dough cup. Top with chopped peppers and shredded mozzarella cheese.
Bake for 15-18 minutes, until cheese is bubbly and dough is lightly browned on top.
Remove from oven and let cool for two minutes before removing to a serving tray.