Preheat the oven to 225 ° C O / U heat. Line a baking sheet with parchment paper.
Clean the mushrooms and cut into slices. Peel the onion and cut into small cubes. Heat oil in a pan. Fry the mushrooms and onion cubes vigorously. Season with salt and pepper. Set aside and let cool down a bit.
Wash and clean the peppers and cut into fine cubes. Wash and slice tomatoes. Halve the small cheese balls.
Knead the minced meat with the egg, breadcrumbs, salt, paprika and pizza seasoning. Then shape 4 flat thalers out of the mince. Fry briefly on both sides in the pan. Remove from the pan and place on the prepared baking sheet. Top with tomato slices, diced paprika, mushroom and onion mixture and mozzarella. Also distribute the remaining vegetables on the tray, season and drizzle with oil.
Bake the pizza meatballs in the preheated oven for about 15 minutes.
Wash the basil, pat dry and cut into fine strips. Sprinkle the mini pizzas with basil and serve on mashed potatoes.