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Ingredients
Scale
- 2½ pounds red potatoes
- 1 medium onion thinly sliced
- 3 tablespoons butter
- 3 tablespoons all-purpose flour
- 1 teaspoon dry mustard powder
- 2 cups milk
- 1 cup shredded cheddar cheese
- ½ cup shredded gruyere cheese
- ¾ teaspoon salt divided
- ½ teaspoon black pepper divided
Instructions
- Preheat the oven to 400°F.
- Wash the potatoes and slice them into ⅛" thin slices. Thinly slice the onion.
- Season the potatoes and onions with ½ teaspoon of salt and ¼ teaspoon of pepper, then toss to coat. Layer the potatoes and onions into stacks and place them on their sides in a greased casserole dish.
- In a saucepan, melt the butter and flour, cooking for 2 to 3 minutes. Add the mustard powder, ¼ teaspoon salt, ¼ teaspoon pepper, and milk. Whisk over medium heat until thick and bubbly. Remove from heat and stir in the cheeses until melted.
- Pour the cheese sauce over the potatoes, gently separating the stacks to let the sauce seep in. Cover with foil (sprayed with cooking spray) and bake for 60 minutes.
- Remove the foil and bake for an additional 20 to 30 minutes until lightly browned and the potatoes are cooked. Cool for 15 minutes before serving.
Notes
Adjust seasoning according to taste, adding more salt or pepper if desired.
For extra flavor, consider adding garlic or herbs to the cheese sauce.
Let the dish cool for the specified time to enhance the flavors.
- Prep Time: 20 minutes
- Cook Time: 125 minutes
- Category: Main Dishes
- Method: Baking
- Cuisine: American
Nutrition
- Serving Size: 1 serving
- Calories: 320
- Sugar: 2g
- Sodium: 640mg
- Fat: 18g
- Saturated Fat: 10g
- Unsaturated Fat: 6g
- Trans Fat: 0g
- Carbohydrates: 32g
- Fiber: 3g
- Protein: 11g
- Cholesterol: 45mg