In a pot with one spoon of butter, sweat an onion that has been sliced. Add one chopped tomato. Stir until they are well mixed.
If it gets too dry, add a dash of water. Next, add one chopped squash and cook for a few minutes. Next add one chopped zucchini and cook for a few minutes as well. Season with 1/2 salt and black pepper.
Next, transfer all the pan contents to a baking dish, and sprinkle as much parmesan as you want. Bake in an oven at 200 Celsius no fan mode for 20 minutes.