Sweet Potato and Leek Gratin for Thanksgiving

Can be made day before, reheat at 300 degrees F. covered. Serves 6

Ingredients

2 large leeks (1 lb total)
2 tablespoons unsalted butter, more for the pan
2 tablespoons olive oil
6 oz pancetta or country ham
1/4 cup minced garlic
2 cups heavy cream
3 tablespoons fresh thyme leaves
1 teaspoon coarse salt
black pepper
2 medium sweet potatoes
3 medium Idaho potatoes


                                                                      Directions

Take the 2 large leeks, trim, half lengthwise, slice 1/4 inch crosswise, swished and soaked in enough cold water to cover. Lift the leeks gently from their soaking water so that any grit stays behind. Drain them in a colander.
In a medium saucepan over medium heat, melt the butter in the olive oil. Add 6 oz pancetta diced in 1/4” pieces, stirring occasionally until golden (about 4 mins). Remove with a slotted spoon and drain on paper towels. If there seems to be too much oil in the pan, pour some of it off at this point, leaving a small amount for the leeks. The dish can become too oily.
Add the leeks and 1/4 cup minced garlic to the pan,cover and reduce the heat to low. Sweat the leeks and garlic, cooking slowly and stirring occasionally until the leeks are softened (about 5 mins). Don’t let the leeks or garlic brown.
Add 2 cups heavy cream. Bring to a boil. Reduce heat and simmer uncovered for 5 mins. Stir in the ham, 3 tablespoons fresh thyme leaves, 1 teaspoon coarse salt and a shake of pepper to taste. Set aside.

Heat the oven to 350 degrees F.
Butter a 2 quart casserole dish (or spray Pam). Peel and slice 2 medium sweet potatoes between 1/4 to 1/8” thick. Repeat with 3 Idaho potatoes,

Arrange one overlapping layer of Idaho slices on the bottom of casserole. Season lightly with salt and pepper. Spoon 2 tablespoons leek cream evenly over the potatoes. Add a layer of sweet potato slices, season lightly with salt and pepper and spoon on another 2 tablespoons of leek cream. Repeat with remaining potatoes until all are used. Press down firmly on the potatoes with hands and drizzle remaining leek cream over them.
Bake until the gratin is golden on top, 50 - 60 minutes.
Let rest in a warm place for 15 min.