
Start by flattening the ground beef meatballs into patties.
Next, on half of these patties place the caramelized onion, the grated cheddar cheese and cover them with the other half of the patties.
Transfer them to the freezer and let them chill for at least 30 minutes.
In a medium bowl, add the tomatoes cut into small cubes, the red bell pepper also cut into small cubes, the grated mozzarella cheese and the mayonnaise.
Season with the salt, the black pepper and mix everything very well until fully combined.
Next, line the bottom of a large baking tray with the potatoes cut into thin slices.
Then season with a pinch of salt and a pinch of black pepper.
Add the mushrooms cut into strips, the mixture we prepared and spread it evenly.
Now, add the meat patties we prepared.
Season the meat with the salt and the black pepper.
Take to a preheated oven at 180° C (350° F) and bake for 40 minutes.
Serve.