Preheat oven to 450 degrees. Unroll both pie crusts. Lay one on a floured surface, sprinkle with rosemary, pepper and ½ cup cheese and place the other pie crust on top. Roll into a 13” circle and press into a 9” springform pan. Fold any extra edges under. Chill while you peel and slice potatoes
Wash and peel the potatoes. Thinly slice with a mandolin or food processor.
Layer 1/3 of the potatoes, a sprinkle of salt, and ¼ cup of cheese. Repeat ending with the potatoes.
In a glass measuring cup microwave heavy cream and garlic for 45 seconds. Pour over the potato layer and sprinkle with ¾ cup cheese.
Cover with aluminum foil and place on a baking sheet. Bake covered for 1 hour. Uncover and bake an additional 30 minutes until crust is browned. Let stand 10-15 minutes to cool before removing the sides of the pan.
Recipe by Supper for a Steal at http://www.supperforasteal.com/potato-gratin/