Side Dishes

Rosemary Scalloped Apple, Celery Root & Sweet Potato Casserole with Marshmallows & Pecans

  • Prep 10 mins
  • Total 1 hour
  • Medium
  • Serves 8

This Rosemary Scalloped Apple, Celery Root & Sweet Potato Casserole with Marshmallows & Pecans is the perfect side dish for your holiday table.

TIP: For quick prep, use a mandoline slicer to slice the apples, celery root, and sweet potato. 


  • Contains Milk/Dairy
  • Contains Tree Nuts

Tip: Allergy Advice

This dish contains the following allergens: Milk/Dairy, Tree Nuts

Cooking mode

Step-by-step instruction without your screen going to sleep

  • 2 tablespoons unsalted butter
  • 1 medium white onion, trimmed, peeled, cut in half then thinly sliced
  • 2 tablespoons all-purpose flour
  • 3 cups half & half
  • 3 Granny Smith apples, peeled, cored, cut in ¼-inch slices
  • 1 large celery root, peeled, cut in half then thinly sliced
  • 1 medium sweet potato, peeled, thinly sliced
  • 2 tablespoons fresh rosemary, chopped
  • Kosher salt, as desired
  • Ground black pepper, as desired
  • 2 cups mini marshmallows
  • 1/2 cup pecans, chopped


  • Whisk
  • Large Bowl
  • Step 1

    Preheat oven to 350°F.  

  • Step 2

    Place the Ninja™ Foodi™ NeverStick™ 3-quart Sauté Pan over medium heat. Add the butter and cook until melted. Add the onions, toss to coat, and continue to cook until slightly caramelized, about 10 to 15 minutes.   

  • Step 3

    Sprinkle the flour over the onion and stir until flour is fully incorporated.  

  • Step 4

    Slowly add the half & half and whisk until mixture begins to thicken. 

  • Step 5

    Transfer the mixture to a large bowl. Then add the apples, celery root, sweet potato, rosemary, salt, and pepper and toss until evenly combined.  

  • Step 6

    Place the mixture back in the pan and spread into an even layer. Cover with the lid and place in the preheated oven to cook until the vegetables are tender, about 35 to 45 minutes.  

  • Step 7

    When cooking is complete, remove the pan from the oven, then remove the lid. Top the casserole with mini marshmallows and pecans. Preheat the oven to broil, then place the pan back in the oven. Cook until the marshmallows are slightly browned, about 2 minutes (keep an eye on them, as they can burn quickly). 

  • Step 8

    When cooking is complete, remove the pan from the oven and let cool for 10 minutes before serving.