Peel the kohlrabi, cut into approx. 0.5 cm thick slices and pre-cook in salted water for 4 - 5 minutes. Drain.
Cut the ham, tomatoes, mozzarella and paprika into small cubes. Put everything in a bowl. Clean the mushrooms, chop them into small cubes and sauté in a pan with a little butter until the liquid has evaporated. Let cool and add to the bowl as well.
Stir in the cream cheese, tomato paste and ketchup, season with salt and pepper.
Cover a baking sheet with parchment paper and spread the kohlrabi slices on top. Place the topping on the kohlrabi slices and sprinkle with grated cheese. Push the tray into the hot oven and bake at 180 ° C top / bottom heat for approx. 25 - 30 minutes.
Place 3 - 4 slices per serving on plates and serve with lettuce.