Clean, wash and cut the peppers and courgettes into pieces. Peel garlic and chop finely. Peel and roughly chop the onions. Drain mozzarella well on a sieve and then cut into slices.
Heat the olive oil in a pan, fry the zucchini and peppers for about 5 minutes, turning them over, and add the garlic and rosemary 1 minute before the end of the frying time. Season with salt, pepper and paprika. Cut out the lid of the flatbread to create a 1 cm wide edge.
Add the vegetables and mozzarella to the flat bread. Bake the flat bread in a preheated oven (electric: 200 °C/ gas: level 3) for about 15 minutes. Sprinkle flat bread with pepper and serve garnished with rosemary as desired.