Cooking tip: Use a food processor to thinly slice potatoes.
- 2 1/2 Pounds yukon gold potatoes, peeled and very thinly sliced (about one sixteenth inch)
- 1/3 Cup melted butter, divided
- 3/4 Teaspoons salt, divided
- 1/4 Teaspoon freshly ground pepper, divided
- 2 Tablespoons all-purpose flour
- 3/4 Cups milk, such as Hood
- 1/2 Cup sour cream, such as Hood
- 1 sprig rosemary, for garnish
Preheat oven to 400 degrees F.
Grease an 8-inch ovenproof skillet. Toss potatoes with 1/4 cup melted butter, 1/2 tsp salt, and pinch pepper until well combined.
In saucepan over medium heat, whisk together remaining butter and flour. Cook for 1 minute. Slowly whisk in milk, remaining salt, and pepper. Bring mixture to boil, then reduce heat and simmer, whisking constantly, for 6 minutes, until mixture thickens. Remove from heat and whisk in sour cream.
Starting in the center of the skillet, arrange one layer of potatoes slices, slightly overlapping, in a circular pattern to cover the bottom of the pan. Add about 3 tablespoons sour cream sauce. Repeat, layering potatoes with sour cream sauce, pressing down to compact layers. Top with sprig of rosemary.
Cover tightly with foil. Bake, covered, for 40 minutes. Remove foil. Continue to bake, uncovered, for 40 to 45 minutes or until potatoes are tender and golden brown. Serve with additional sour cream. Slice into wedges and serve.