Potato Gratin

8 c. very thinly sliced potatoes (Use either red potatoes or russet baking ones. I use the food processor to slice them and leave the skins on.)

2 c. thinly sliced yellow onions

2 cups + 2 Tbsp. heavy cream

2 1/2 c. grated Gruyère cheese (about 1/2 lb), divided

1 Tbsp. olive oil

1 Tbsp. butter or bacon grease

1 tsp. salt

1/2 tsp. freshly ground black pepper

Slice the onions very thin. Heat a skillet over low/medium heat; add the olive oil and butter (or bacon grease). Spread the onions out in the skillet and let them slowly caramelize, stirring every few minutes. Remove from the heat when they are soft and golden brown, about 15-20 minutes. 

The food processor makes shredding the cheese and slicing the potatoes a cinch, but you can certainly do both by hand. I love the added color and texture provided by the skins, but if you prefer, peel the potatoes. Divide the shredded Gruyère; place 2 cups in a large bowl and the other 1/2 cup in a small bowl. Add two cups of heavy cream to the large bowl and stir two tablespoons of cream into the 1/2 cup of cheese, reserving this for the topping. 

Stir the sliced potatoes, caramelized onions, salt and pepper into the large bowl of cream and cheese, gently stirring until everything is coated. Pour the mixture into a buttered casserole dish (approximately 9 x 13 inches). Pressed down firmly on the top of the potatoes. Sprinkle the little bowl of cheese and cream on the top of the casserole, to form that nice, finishing crust. 

At this point, you can cover the dish with foil and refrigerate it for several hours before baking, or it can go right into the oven. Using convection bake, preheat the oven to 325 degrees, and bake for about 1 hour and 20 minutes (regular bake at 350 for 1 1/2 hrs). The finished gratin should be quite brown and bubbly; check after an hour and lay foil over top if necessary to prevent excessive browning. Let set for at least ten minutes before serving. Serves 8-10