Vidalia Onion & Potato Casserole

Name: Vidalia Onion & Potato Casserole
Cook time: 1 h 20 min
Total time: 1 h 20 min
Cuisine: European, American
Ingredients: 2 lbs waxy potatoes (like Yukon gold), peeled and sliced very thin, about 1/8 inch thick; 3 sweet Vidalia onions, thinly sliced; 2 cups heavy cream; 1 cup mild or medium cheddar cheese, grated; 1 clove garlic; 1 sprig rosemary; 1 sprig thyme; 2 tablespoons olive oil; 1 tablespoon butter, plus more for greasing dish; kosher salt and freshly ground pepper, to taste