Preparation Steps
Preheat oven to 450.
Unroll piecrusts on a lightly floured surface.
Sprinkle rosemary, pepper, and cup cheese over 1 piecrust; top with remaining piecrust.
Roll into a 13-inch circle.
Press on bottom and up sides of a 9-inch springform pan; fold edges under.
Chill.
Meanwhile, peel and thinly slice Red potatoes, sweet potatoes, carrots and turnips.
Layer one-third each of red potatoes, sweet potatoes, carrots and turnips and salt in prepared crust.
Sprinkle with cup cheese.
Repeat layers twice, pressing layers down slightly to fit.
Microwave cream and garlic in a 1-cup microwave-safe measuring cup at HIGH 45 seconds; pour over potato layers in pan.
Sprinkle with remaining cup cheese.
Cover pan with heavy-duty aluminum foil.
Place on a baking sheet.
Bake at 450 for 1 hour.
Uncover and bake 25 minutes or until potatoes are done and crust is richly browned.
Let stand 10 to 15 minutes.
Carefully transfer to a serving plate, and remove sides of pan.
If desired, carefully slide gratin off bottom of pan using a long knife or narrow spatula.