In a large bowl, whisk together flour, baking powder, Italian seasoning and salt. Make a well in the centre. Whisk together oil, milk, eggs and pour into well. Stir until just moistened.
Stir in cheese, red pepper and pepperoni. Divide among 12 paper-lined muffin cups.
Sprinkle cheese over muffins. Top with pepperoni pieces and 1 tomato half, cut side up..
Bake in 375°F oven for about 25 minutes or until the tops are firm to the touch.