A rich and comforting Sweet Potato Gratin featuring smoked gouda, fresh rosemary, and warm spices—perfectly creamy with a golden, cheesy crust.

3 lbs sweet potatoes, peeled and sliced ⅛-inch thick

4 tablespoons unsalted butter

2 cloves garlic, minced

1 small red onion, finely diced

1 tablespoon all-purpose flour

1 cup heavy cream

1 cup half and half (or whole milk)

½ tablespoon fresh rosemary, finely chopped

1 teaspoon smoked paprika

¼ teaspoon ground sage

¼ teaspoon freshly grated nutmeg

½ teaspoon Diamond Crystal kosher salt

¼ teaspoon freshly ground black pepper

⅓ cup grated asiago cheese

1 cup shredded smoked gouda cheese, divided

1 cup shredded Colby Jack cheese, divided

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1. Preheat your oven to 400°F.

2. Melt butter in a large saucepan over medium heat.

3. Add garlic and red onion; sauté for about 5 minutes until softened and fragrant.

4. Stir in the flour to form a paste; cook for 1 minute.

5. Gradually whisk in heavy cream and half and half; simmer for 3–4 minutes until thickened.

6. Remove from heat and stir in asiago cheese, rosemary, paprika, sage, nutmeg, salt, and pepper.

7. Let the sauce cool slightly.

8. Peel and slice sweet potatoes into ⅛-inch rounds.

9. Grease a 9×13 baking dish and arrange the potatoes in overlapping layers.

10. Stir half of the smoked gouda and half of the Colby Jack into the cooled sauce.

11. Pour sauce evenly over the potatoes and top with remaining cheese.

12. Cover with foil and bake for 45–50 minutes until potatoes are tender.

13. Uncover and bake for an additional 15–20 minutes until golden and bubbling.

14. Optional: Broil for 1–2 minutes for a crispier top.

15. Let the gratin rest for 10–15 minutes before serving.

Use a mandoline for evenly sliced potatoes to ensure uniform cooking.

For a lighter dish, swap half and half with whole milk.

Assemble the gratin in advance and refrigerate until ready to bake—just increase bake time slightly.

Fresh rosemary is key—dried won’t deliver the same depth.

Watch closely if broiling at the end to prevent burning.