How it’s done
First, preheat the oven to 180°/circulating air. The vegetables and potatoes are cut into thin slices. In a saucepan, melt the butter/margarine and then stir in the flour. Immediately after, add the milk and mix well with a whisk to make a thick sauce. Then add the chunky tomatoes, season with salt and pepper and the frozen herbs. Stirring constantly, the sauce should boil briefly.
Now cover the bottom of the baking dish with all the sauce. Then, on top of the sauce, place the slices of vegetables and potatoes close together in rows. Shortly before baking, sprinkle some salt as needed over the vegetables, chop the mozzarella and sprinkle it over the vegetables as well. Now everything is baked in the oven for about 40 minutes (baking time varies depending on the oven). When the gratin is done baking, it is removed from the oven and should cool for a few minutes. Then the fresh thyme is chopped with a knife and sprinkled over the gratin as a finish. And then it's time to say Bon Appétit♥️.
