
Start by placing the ground beef into a large grater.
Transfer it to a large pot over medium heat with the medium onions in boiling water.
Cover the pot and cook for 5 minutes.
After this time has passed, remove the meat from the pot and cut it into 6 equal slices.
Also cut the onions we cooked into rings and set aside.
In a medium bowl, add the finely diced tomatoes, the mushrooms cut into smaller pieces, the grated mozzarella cheese and the mayonnaise.
Season with the salt, the black pepper and mix everything very well until fully combined.
To assemble the recipe, line the bottom of a large baking tray with the potatoes cut into thin slices.
Season with the salt and the black pepper.
Add the onions we cut earlier, the mixture we prepared and spread evenly.
Next, add the slices of meat and make a hole in each one using a rolling pin.
In each hole made in the meat, add one cube of cheddar cheese and one egg yolk.
Season with salt and black pepper to taste.
Add the grated mozzarella cheese over everything.
Place in a preheated oven at 180° C (350° F) and bake for 35 minutes.
Serve.