Potato gratin with lean ground meat

Preparation

1. Preheat oven to 375ºF (180ºC).
2. Spray a 9x13-inch casserole dish with nonstick cooking spray. Arrange half the potato slices in the bottom of the dish and season as needed with salt and black pepper. Set aside.
3. Spray a large skillet with nonstick cooking spray and set it over medium-high heat. Add ground meat and diced onion. Saute for 7-8 minutes, breaking up the meat with a spatula as it cooks, until it is browned and the onion is softened. Add the minced garlic, thyme, salt, and black pepper.
4. Remove the skillet from the heat. Spoon meat mixture evenly over the potato slices in the casserole dish.
5. Return the skillet to the heat and add the butter. Once the butter is melted, sprinkle the flour into the pan and whisk to form a paste. Cook for 30 seconds to a minute, then slowly pour the cream into the pan, whisking to dissolve the flour.
6. Cook the sauce, whisking constantly, until it begins to bubble and thicken. Once thickened, turn off the heat and set aside. Add salt and black pepper as needed.
7. Pour half the sauce over the ground meat mixture.
8. Arrange the remaining potato slices in an even layer on top and season with salt and pepper.
9. Pour the remaining sauce over the potatoes and sprinkle the shredded cheese evenly over the dish.
10. Cover the casserole dish loosely with aluminum foil.
11. Bake for 35 minutes on the middle rack of the oven.
12. Remove the aluminum foil and continue baking for 20-25 minutes, until the potatoes are fork-tender and the cheese is lightly browned on top.
13. Allow to rest for 10-15 minutes before serving.
14. Portion into serving plates and garnish each plate with fresh rosemary.