Instructions
Step 1. Preheat & Prep:
- Preheat your oven to 375°F (190°C).
- Lightly grease a 9×13-inch baking dish or casserole pan.
Step 2. Slice the Potatoes:
- Peel and thinly slice the potatoes (about â…›-inch thick) using a sharp knife or mandoline.
- Place slices in cold water to prevent browning while you prepare the sauce.
Step 3. Make the Creamy Cheese Sauce:
- In a saucepan over medium heat, melt butter.
- Add chopped onion (if using) and cook for 2–3 minutes until soft.
- Stir in garlic and cook for another 30 seconds.
- Add flour and whisk constantly for 1–2 minutes to form a roux.
- Slowly pour in warm milk and cream while whisking to avoid lumps.
- Cook for 3–4 minutes until the sauce thickens slightly.
- Stir in salt, pepper, paprika, cheddar, and Parmesan cheese. Mix until smooth and melty.
Step 4. Assemble the Dish:
- Drain the sliced potatoes and pat them dry with a paper towel.
- Arrange half of the potato slices in the bottom of the baking dish.
- Pour half of the cheese sauce over the top.
- Add the remaining potatoes and then the rest of the sauce.
- Sprinkle extra shredded cheddar on top if desired.
Step 5. Bake:
- Cover with foil and bake for 40 minutes.
- Remove foil and bake for another 15–20 minutes until golden and bubbly.
- Let it rest for 10 minutes before serving (this helps it set).