Creamy Rosemary Au Gratin Potatoes - cooking recipe

Ingredients

3 tablespoons butter, divided
3 tablespoons all-purpose flour
1/2 teaspoon sea salt
2 cups half-and-half
4 russet potatoes - scrubbed, unpeeled, and cut into 1/4-inch slices
1 onion, sliced into rings
1 tablespoon chopped fresh rosemary
1/2 cup shredded Cheddar cheese
sea salt and ground black pepper to taste
1 cup shredded Cheddar cheese
1 pinch paprika

Preparation

Preheat oven to 400 degrees F (205 degrees C). Grease a 1-quart baking dish with about 1 teaspoon butter.
Melt remaining butter in a saucepan over medium heat. Add flour and 1/2 teaspoon sea salt; whisk constantly for 1 minute. Pour half-and-half into flour mixture, stirring and cooking until mixture has thickened, about 4 minutes.
Layer half the potatoes into the bottom of prepared baking dish. Top with onion slices, rosemary, 1/2 cup Cheddar cheese, and remaining potatoes; season with sea salt and pepper. Sprinkle 1 cup Cheddar cheese and paprika over potatoes. Pour half-and-half mixture over potato mixture; cover with aluminum foil.
Bake in preheated oven until potatoes are tender, about 75 minutes. Remove aluminum foil and continue baking until potatoes are lightly browned, about 15 minutes.