Gratin potatoes (Thanksgiving side dish)

These potatoes are used, amongst many other recipes, as side dish for Thanksgiving

INGREDIENTS (6 servings):

• 4 or 5 large potatoes 
• 1 large red (sweet) onion
• 2.5 cups (500 ml) of milk
• 1 cup (250 grams) of cheddar cheese grated
• 3 tablespoons of butter
• A tablespoon of white flour
• Bread crumbs
• Salt
• Pepper

First we are going to prepare the sauce. We melt the butter in a pan and with it we fry the onion that we have previously chopped. When transparent, we add the tablespoon of flour. 

Add little by little, while stirring, all the milk and 3/4 of cheddar cheese and keep over low heat until it thickens. It is time to season and remove from heat. It is basically making a kind of bechamel sauce.

We cut the potatoes into finger-thick slices. We take them to a deep dish and season them. Pour the previously obtained sauce over the potatoes and sprinkle the rest of the grated cheddar cheese and a little breadcrumbs on the surface.

We preheat the oven to 190 degrees (374 F) and put the potatoes in for an hour. After that time we connect the grill for twenty minutes until the top turns brown.

Serve hot.