1 large butternut squash, peeled and sliced into 1/8 inch rounds
2 russet potatoes, peeled and sliced into 1/8 inch rounds
3 T olive oil
6 cloves garlic, minced
2 tsp fresh thyme, minced
1 tsp salt
1/2 tsp freshly ground pepper
4 T butter
1 1/2 c heavy cream
1/2 c whole milk
1 1/2 c shredded gruyere
1 c shredded Parmesan
Preheat oven to 425 degrees and grease 8 x 8 casserole dish.
Peel the butternut squash and potatoes.
Using a mandolin or very sharp knife, cut the squash and potatoes into 1/8 inch thick rounds or half rounds and place into a large mixing bowl. Toss with a few T olive oil.
Heat a saucepan over medium heat. Add butter, cream, milk, and garlic. Cook until butter is melted, stir in fresh thyme, and set aside.
Start layering the potatoes and squash into the dish, alternating colors in 1 even later. Top each layer with salt, pepper, a little gruyere and parmesan. Repeat until you use up all of the taters and squash.
Pour the cream mixture all over the potatoes and squash, and sprinkle the top with the remaining gruyere and parmesan.
Cover gratin with foil and bake for 25 minutes. Remove the foil and bake an additional 25-30 minutes, or until top is golden brown and bubbling.