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Brussels Sprouts and Potato Gratin
4.74 from 15 votes

Brussels Sprouts and Potato Gratin

This ultra-creamy Brussels Sprout and Potato Gratin Recipe with Crispy Fried Onions is the perfect holiday side dish for even the pickiest of veggie eaters. Made with real ingredients (no canned soup), Brussels sprouts, potatoes, and gooey melted gruyere and cheddar cheese, this beautiful gratin is guaranteed to be a new holiday favorite!
Prep Time25 minutes
Cook Time25 minutes
Total Time50 minutes
Servings: 8 servings
Calories: 306kcal


  • 1 pound Honey Gold Potatoes - sliced into 1/4" rounds
  • 1 pound Brussels sprouts - halved
  • 3 tablespoon butter
  • 3 large shallots - minced
  • 1 teaspoon fresh thyme - chopped
  • 1 teaspoon fresh rosemary - minced
  • 5 cloves garlic - minced
  • 1 tablespoon flour
  • 3 tablespoon sweet marsala wine
  • ¾ cup whole milk
  • ½ cup half and half
  • ½ cup shredded Gruyere
  • 1 cup shredded sharp cheddar
  • salt + pepper - to taste
  • 1 ½ cups fried onions


  • Preheat oven and bring a large pot of salted water to a boil. Preheat oven to 375 degrees F and bring a large stockpot of salted water to a boil.
  • Blanch the Brussels sprouts and potatoes. Halve Brussels Sprouts and slice potatoes into 1/4" rounds. Add the Brussels Sprouts and potatoes to the pot and boil for 3-4 minutes (do not overcook or the potatoes will not maintain their shape and the Brussels sprouts will lose their bright green color). Drain and immediately transfer to a large pot filled with ice water to stop cooking and set the color of the vegetables. When the sprouts are cooled, drain. Set aside.
  • Make roux. Meanwhile, melt butter in a large skillet over medium-high heat. Add the minced shallots and sauté for 3-4 minutes. Add the fresh thyme, rosemary, and garlic and sauté for 1 minute more. Reduce heat to medium and sprinkle the flour on top of the vegetables. Stir to combine, taking care not to burn the flour. Add the marsala wine and whisk well to combine. Cook for one more minute.
  • Finish the sauce. Add the milk and half-and-half to the skillet and whisk well until the sauce is smooth and thickened. Remove from heat and mix in half of the shredded cheese until completely smooth and melted. Season with salt and pepper. Add the Brussels Sprouts and potatoes to the cheese sauce and mix well to combine.
  • Transfer to a gratin dish and bake. Transfer to a greased 8x10 baking dish and cover loosely with foil. Bake for 30 minutes. Sprinkle with fried onions and the remaining shredded cheese and put under the broiler until the cheese is brown and melted.


  • It's best to use Brussels sprouts that approximately equal in size. If you have really big sprouts, quarter those and halve the smaller ones.
  • Although gratin recipes are typically baked in gratin pans, it is not required. Use whatever baking dish is most convenient for you.
Originally published November 15, 2017


Calories: 306kcal | Carbohydrates: 21g | Protein: 10g | Fat: 19g | Saturated Fat: 10g | Cholesterol: 43mg | Sodium: 278mg | Potassium: 566mg | Fiber: 3g | Sugar: 3g | Vitamin A: 880IU | Vitamin C: 56.3mg | Calcium: 275mg | Iron: 2.9mg
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