Preheat the oven to 375 degrees. Prepare a large baking dish by lightly spraying with non-stick cooking spray {I just use olive oil and my Misto}, then arrange the spiralized sweet potatoes and apples in the dish to fit. Set aside.

In a large skillet, melt 4 tablespoons butter over medium heat, melt butter. Once melted, sprinkle flour over top and whisk until a paste forms. Cook for about a minute.

Slowly add milk, whisking to make sure there are no lumps. Add smashed garlic clove and let bubble until thickened, about 2-3 minutes.

Add the cheese and continue to whisk until it is completely melted and the sauce is smooth. Whisk in the nutmeg and salt to taste.

Pour the sauce directly over top of the spiralized sweet potatoes and apples, gently giving them a shake to help the sauce settle down into the spirals and smooth out the top.

In a small bowl, prepare the topping by melting the remaining 2 tablespoons of butter and tossing with the Panko bread crumbs and chopped pecans until they're fully coated.

Evenly cover the top of the gratin with the mixture, then cover with foil and bake for about 35-40 minutes or until the sweet potato and apple spirals are tender and the cheese sauce is bubbly around the edges.

Remove the foil and allow to bake uncovered for another 5-8 minutes or until the top is browned and crunchy. Serve hot!