Creamy Cheesy Sweet Potato Gratin

Prep: 15 minCook: 55 minmedium
Creamy Cheesy Sweet Potato Gratin

A rich, comforting side dish featuring layers of tender sweet potato slices bound in a silky cheese sauce and topped with melted mozzarella. The béchamel base provides creamy decadence while herbs add fresh brightness. Perfect for holiday tables, weeknight dinners, or as a vegetarian main alongside a salad. This version balances sweetness with savory umami for a sophisticated take on classic potato gratin.

VegetarianNut-Free

Ingredients

  • 4 sweet potatoes, peeled and sliced
  • 5 tbsp unsalted butter
  • ½ cups wheat flour
    cornstarch1:1gluten-freegluten-free

    whisk well to prevent lumps

    Full guide →
  • 1 ¾ cups milk, whole
    vegetable broth1:1vegandairy-free

    omit butter and cream, use olive oil

    Full guide →
  • ¾ cups table cream, heavy cream
    crème fraîche1:1dairydairy-free

    adds slight tanginess

    Full guide →
  • 1 teaspoon salt
  • 1 pinch black pepper, ground
  • 1 ¾ cups mozzarella cheese, grated
    cheddar1:1cheese

    sharpness increases

    Full guide →
  • parsley, fresh, chopped(optional)
  • chives, fresh, chopped(optional)

Instructions

  1. 1

    Cut sweet potatoes into round slices.

  2. 2

    Melt butter in a skillet over medium heat.

  3. 3

    Stir in wheat flour until incorporated.

  4. 4

    Add milk and stir until creamy.

  5. 5

    Add table cream and stir to combine.

  6. 6

    Season with salt and black pepper.

  7. 7

    Transfer potatoes to a large baking dish.

  8. 8

    Pour cream sauce over potatoes.

  9. 9

    Cover dish with aluminum foil.

  10. 10

    Bake at 350°F for 45 minutes.

  11. 11

    Uncover and top with grated mozzarella.

  12. 12

    Return to oven until mozzarella melts.

  13. 13

    Sprinkle with fresh chives and parsley.

  14. 14

    Serve hot.

Tips

Tip 1

Slice potatoes uniformly (about 1/4-inch) so they cook evenly in the 45-minute window.

Tip 2

Whisk flour into melted butter thoroughly to avoid lumps before adding liquid.

Tip 3

Keep mozzarella in the freezer until ready to top so it doesn't clump.

Good to Know

Storage

Cover and refrigerate up to 3 days. Reheat covered at 160°C for 15 minutes.

Make Ahead

Assemble (potatoes, sauce, foil cover) up to 8 hours ahead. Bake fresh or add 10 minutes to cook time if chilled.

Serve With

Hot, directly from the baking dish. Pair with roasted chicken, grilled fish, or a winter salad.

Common Mistakes

Watch

Do not skip whisking flour into butter to avoid lumpy sauce.

Watch

Do not overbake before adding mozzarella or potatoes may dry out.

Watch

Do not use low-moisture mozzarella or it will not melt smoothly.

Substitutions

Dairy-Free Swaps

table cream→
crème fraîche1:1dairydairy-free

adds slight tanginess

Full guide →
milk→
vegetable broth1:1vegandairy-free

omit butter and cream, use olive oil

Full guide →

Gluten-Free Swaps

wheat flour→
cornstarch1:1gluten-freegluten-free

whisk well to prevent lumps

Full guide →

General Alternatives

mozzarella→
cheddar1:1cheese

sharpness increases

Full guide →
Find more substitutions →

FAQ

Can I make this ahead and freeze it?

Yes. Assemble completely before baking, wrap tightly, and freeze up to 1 month. Bake from frozen, adding 15-20 minutes to total time, covered.

What if the mozzarella isn't melting evenly?

Ensure cheese is at room temperature before topping and that oven heat is even. If needed, broil for 1-2 minutes, watching closely to avoid scorching.

How long can I keep leftovers?

Refrigerate covered for up to 3 days. Reheat covered at 160°C for 15 minutes or until warmed through.