Let the oil get hot in the pan and peel the onion and dice 2/3 of it.
Preheat the oven to 200 degrees (convection).
Fry the onion cubes in the pan until translucent and add the minced meat. Fry everything well and season well with salt and pepper.
Add the ketchup and mustard and mix everything together.
Pull the Knack & Back rolls apart and place in the greased muffin tin. Pour the minced meat mixture into the muffins and put the tin in the oven for approx. 5 - 7 minutes.
As soon as the dough has risen a little, take out the muffins and sprinkle the cheese over them in small pieces. Put the muffins back in the oven for a few more minutes, until the cheese has melted nicely.
Take the muffin tin out of the oven and let the cheeseburger muffins cool down a little
Finally, decorate the muffins with pickles, lettuce and onions or whatever else you want on top.