Cheesy Ground Beef and Potato Casserole

step 1 Preheat oven to 375°F (190°C). Grease a 9×13-inch baking dish with butter or olive oil.
step 2 In a large skillet, cook ground beef and diced onion over medium heat until beef is browned. Drain excess grease.
step 3 Stir in garlic powder, onion powder, salt, and pepper. Remove from heat.
step 4 In a separate bowl, mix cream of mushroom soup with milk until smooth.
step 5 Layer half of the sliced potatoes in the baking dish. Spread half the beef mixture over the potatoes, then pour over half of the soup mixture. Sprinkle with 1 cup of cheddar cheese.
step 6 Repeat the layers with remaining potatoes, beef, soup mixture, and top with mozzarella and the rest of the cheddar.
step 7 Cover with foil and bake for 60 minutes. Remove foil and bake an additional 15-20 minutes until potatoes are tender and cheese is golden and bubbly.
step 8 Let rest for 10 minutes before serving. Garnish with fresh thyme or parsley if desired.

Storage and Reheating Tips.

Store leftovers in an airtight container in the refrigerator for up to 4 days. Reheat individual portions in the microwave, or reheat the whole casserole in the oven at 350°F until warmed through. Freeze tightly wrapped portions for up to 2 months and thaw overnight before reheating.