Oh-My Loaded Meatloaf Casserole

Ingredients

• 1 1/2 pounds ground beef
• 1/4 yellow onion, finely chopped
• 2/3 cup seasoned dry breadcrumbs
• 1/3 cup whole milk
• 1 large egg, lightly beaten
• 1/2 teaspoon kosher salt
• 1/4 teaspoon coarse ground black pepper
• 2 pounds potatoes, peeled and cut into 1-inch chunks
• 1/3 cup unsalted butter
• 1/2 cup whole milk
• 1 teaspoon salt
• 1/2 teaspoon coarse ground black pepper
• 1 cup cheddar cheese, shredded
• 1/2 cup bacon bits, cooked and crumbled