Sweet Potato Onion Gratin-in the pan-whole

Sweet Potato Onion Gratin

  • Author: Loreto
  • Prep Time: 35 minutes
  • Cook Time: 1 hour 10 minutes
  • Total Time: 1 hour 45 minutes
  • Yield: serves 6-8 people 1x
  • Category: grilling/baking
  • Method: barbecue/oven
  • Cuisine: American
  • Diet: Vegetarian


Sweet Potato Onion Gratin.  Take grilled sweet potato and onion and layer it is a baking dish separated by gooey cheese and cream spiced with grated horseradish and we have a side dish that will take you on the flavor town express! This dish has layer upon layer of taste bud tantalization surely making it a winner in my books!


  • 2 large sweet potatoes peeled, washed, and dried and cut into 1/2 inch thick rounds
  • 2 medium Vidalia onions peeled and cut into 1/2 inch thick rounds
  • 1/4 cup canola oil
  • 2 Tbsp  unsalted room temperature butter
  • 1 1/2 cups half & half cream
  • 1/2 cup whipping cream
  • 4 Tbsp grated horseradish
  • 2 Tbsp dried thyme
  • 1 tsp dried oregano
  • 2 1/2 cups grated Gruyere, Gouda, Asiago cheese mixed
  • Salt, and pepper



  1. Pre-heat grill to medium to high heat. Pre-heat oven to 350 degrees F. Then grease a 9 x 13-inch baking dish with some butter.
  2. In a baking sheet sprinkle some oil over the onions and sweet potatoes and season with salt, pepper.
  3. Place sweet potatoes and onions on a vegetable cookie sheet on the grill and cook till veggies are slightly charred and cooked halfway. Roughly 2 minutes a side.


  1. In a large bowl combine half & half cream, whipping cream, horseradish, salt and pepper, 2 tsp salt and 1 tsp black pepper, thyme, and oregano. Blend well.


  1. Sprinkle some of the cheese mixture into the bottom of the greased baking dish. Layer 1/3 of the sweet potato and onion then sprinkle some cheese and repeat until you get three layers.
  2. Finish the top with more cheese blend. Then slowly pour the cream mixture over the top.


  1. Cover the dish with foil paper and bake in the oven for  35-40 minutes. Uncover and bake for an additional 15 to 20 minutes. Take out of the oven and let rest 15 minutes prior to serving.
  2. Ready to serve.



You can use any cheese you have on hand, preferably one that is a good melting cheese.

If you don’t like horseradish, substitute some grated ginger or garlic.

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