Sweet Potato, Apple and Leek Casserole

Deselect All

2 tablespoons olive oil

2 medium leeks, white and light green parts sliced lengthwise and thinly sliced crosswise 

Salt and freshly ground pepper 

1 tablespoon fresh thyme leaves 

1/2 cup heavy cream 

1 large sweet potato (about 1 pound), peeled and sliced into 1/2-inch-thick rounds 

1 large or 2 medium red skinned apples, such as Gala or Honeycrisp (about 12 ounces), halved, cored and cut into 1/4-inch slices 

1/4 cup freshly grated Parmesan