How to make
Leave the green beans to thaw and chop them. Heat 1 1/3 tbsp (20 g) butter and braise the finely chopped leeks until softened. Add the remaining vegetables, finely chopped, and cook 15 min. on low heat without a lid.
Season with salt and black pepper. In a separate container, heat the remaining butter and braise the flour. Gradually pour in the milk, bring to a boil and boil 4-5 min. on low heat. Then add the grated cheese and stir well. Grate the potatoes on a coarse grater.
Pour some sauce on the bottom of a deep oven dish, place 1/3 of the veggies on top, cover with 1/2 of the grated potatoes. Repeat until you run out of products and bake 40 min. in a preheated 390°F (200 °C) oven.
