Preheat your oven to 375°F (190°C). Grease a baking dish lightly with cooking spray.
Heat olive oil in a skillet over medium heat. Sauté onion until softened, then add ground beef. Cook until browned, seasoning with salt and pepper. Drain any excess grease.
In a small bowl, mix the cream soup with milk to create a smooth sauce.
Layer half of the potato slices in the baking dish, followed by half of the beef mixture, half of the broccoli, and half of the sauce. Repeat the layers, finishing with shredded cheddar cheese on top.
Cover with foil and bake for 30 minutes. Remove foil and bake an additional 15 minutes, or until the potatoes are tender and the cheese is bubbly.
Let cool slightly before serving.
Chef Tip: Add a sprinkle of paprika or red pepper flakes for a kick of flavor!