Line 6 hollows of a muffin tin with a slice of ham each. Scatter some cheese in the hollows and distribute the beaten eggs over the 6 hollows. Sprinkle some more cheese on top and bake the tartlets at 180 degrees for about 15 minutes.
That is the basic recipe. The muffins are also delicious with a little steamed leek or with small diced paprika. The imagination knows no limits.
PS: If you prefer cooked ham, you can use the very thinly sliced small slices. However, you then need more than three slices per well.