This recipe is gluten and lactose-free, but if you don’t have specific dietary needs that require the total exclusion of gluten and lactose, you can replace cornstarch with all-purpose flour and use traditional milk and butter.

You can use either boiled or raw potatoes, to be thinly sliced, about 1/25 inch thick.

In the case of boiled potatoes, it is essential that they are cold from the fridge and firm, otherwise, it would be impossible to slice them.

Peel the potatoes (whether cooked or raw), slice them, and keep them on a plate.

Clean the champignon mushrooms (you can also use cooked ones, provided they are free of cooking liquid), removing all dirt and non-edible parts.

Slice them about 1/12 inch thick. After slicing them all, put them in a pan without adding anything, neither water nor condiments.

Cover the pan, place it on a medium burner, and over high flame, wait for them to release their vegetation water (about a minute).

Without burning yourself, remove the mushroom water, put them back in the pan, and repeat this operation two more times (it will take a maximum of 5/8 minutes). It’s important that the mushrooms are dry for this recipe. It’s not necessary to salt the mushrooms and potatoes as they will be flavored by the béchamel.

Prepare the béchamel by melting the butter over low heat in a saucepan.

As soon as the butter is completely melted, add the cornstarch or flour (already sifted), quickly mix with a steel whisk, toasting the flour (or starch) for about 30 seconds before adding all the milk.

Stirring very often and keeping the flame low, flavor the béchamel with a grating of nutmeg, a pinch of curry, and fine salt to taste, keeping in mind that potatoes and mushrooms will also need to be flavored.

To give an extra touch, you can dissolve 50 grams of soft gorgonzola in the hot béchamel.

As soon as the sauce starts to thicken, turn off the heat and remove the saucepan from the burner.

Preheat the oven to 392°F.

Now all that’s left is to assemble the casserole in layers, first spreading a generous spoon of béchamel on the bottom of the baking dish (a round one of 10 inches or an oblong one of 12 inches, like mine in the photo) and alternating:

-1 layer of potato slices (slightly overlapping each other)

-1 spoon of béchamel to gently spread over the potatoes

-1 sprinkle of grated cheese

-1 pinch of paprika (sweet or hot)

– 1 portion of mushrooms

-1 another spoon of béchamel and so on, until all the ingredients are used up.

Bake the dish on the middle rack for 25 minutes. At the end of cooking, turn on the grill to create a tempting crust that will make this delicious casserole even more appetizing.

Serve the baked potato and mushroom casserole with a sprinkle of fresh chopped parsley or celery leaves.

If any potato slices are left over, add them along the edges of the casserole, inside the dish, to avoid wasting anything.

Bon appetit