Wash the mushrooms and tomatoes and dry with a paper towel. Prepare other ingredients called for in the recipe. Preheat the oven to 180°C.
Chop the garlic. Cut the tomatoes into medium cubes.
Cut the mozzarella into medium-thick slices. You will need 8-10 slices.
Separate the champignon stems from the caps. Remove the champignon pulp with a spoon or knife - this way more filling will fit.
Place the mushroom caps in a baking dish, pre-greased with oil. Place the pan in the oven and bake the mushrooms for 10 minutes at 180°C.
Remove the mushrooms from the oven and stuff them in the following order: garlic, mozzarella, tomatoes.
Cover each cap with a slice of processed cheese and place the mushrooms in the oven for 10 minutes at 180°C.
Serve the champignons hot, garnished with finely chopped fresh herbs.
Hot stuffed mushrooms can easily replace a full lunch or dinner; when cold, such mushrooms can be served on lettuce leaves or a bed of arugula.