For the liver cheese muffins with melted tomatoes cut liver cheese into very small cubes, preheat oven to 180 °C.
In a bowl, mix flour with baking powder and add milk, eggs, liver cheese, grated cheese and parsley and mix everything well.
Season with salt, pepper and mustard.
Line muffin tins with melted butter (or use coated paper capsules) and fill the mixture not too full (rises by a good third during baking).
Bake for about 20-30 minutes, depending on the size of the molds.
Remove and let cool briefly.
While the muffins are in the oven, peel the tomatoes as desired (to do this, dip them briefly in boiling water, lift them out and peel off the skin) and cut them into approx. 1 cm cubes. Finely chop the onions as well.
Sauté the young onions together until the tomatoes are nicely “melted”. Season well with salt and pepper, add vinegar to taste, remove from heat and let cool. Cut the basil into strips. Arrange the warm muffins on plates. Arrange tomatoes around the muffins, sprinkle the meatloaf muffins with melted tomatoes with basil and serve.