Slice the Potatoes: Using a sharp knife or mandoline, thinly slice the potatoes. The thinner, the better, as this will help them cook evenly and soften within the casserole.
Step 3: Layer the Casserole
Layer Potatoes: In your prepared baking dish, place a layer of sliced potatoes at the bottom.
Add Beef: Spoon half of the cooked beef mixture evenly over the potatoes.
Add Cheese: Sprinkle a layer of shredded cheese over the beef.
Repeat Layers: Add another layer of potatoes, beef, and cheese until all ingredients are used, finishing with a top layer of potatoes.
Step 4: Make the Sauce
Mix Soup and Milk: In a bowl, whisk together the cream of mushroom soup and milk until smooth.
Pour Over Casserole: Pour this mixture evenly over the layered casserole. This creamy sauce will add flavor and keep the casserole moist as it bakes.
