3 lbs sweet potatoes, peeled and sliced into 1/8 inch rounds
4 tablespoons butter
3 cloves garlic, minced
1/4 cup all purpose flour
1 1/2 cups whole milk
1 cup heavy cream
1 teaspoon fresh thyme leaves
1/2 teaspoon ground nutmeg
1 teaspoon salt
1/2 teaspoon black pepper
1/2 cup grated parmesan cheese
Instructions
Preheat your oven to 375 degrees Fahrenheit and generously grease a 9 by 13 inch baking dish with butter or a light coating of oil. Peel your sweet potatoes and slice them into uniform rounds, about one eighth of an inch thick, using a sharp knife or a mandoline for the best results.
In a medium saucepan, melt the butter over medium heat. Once the butter is bubbling, add the minced garlic and cook for about one minute until it becomes fragrant, being careful not to let it brown or burn.
Whisk the all purpose flour into the melted butter and garlic, cooking for another minute to remove the raw flour taste. Slowly pour in the milk and heavy cream while whisking constantly to ensure no lumps form. Continue to cook and stir until the sauce thickens enough to coat the back of a spoon.
Remove the saucepan from the heat and stir in the salt, black pepper, nutmeg, and fresh thyme. Add half of the parmesan cheese into the sauce and stir until it has melted completely into the mixture.
Arrange the sweet potato slices in the prepared baking dish, either by layering them flat or overlapping them slightly in rows for a beautiful presentation. Pour the creamy sauce evenly over the top of the potatoes, using a spatula to ensure the sauce gets between the layers.
Cover the baking dish tightly with aluminum foil and bake for 40 minutes. This traps the steam and ensures the potatoes become perfectly tender. After 40 minutes, remove the foil, sprinkle the remaining parmesan cheese over the top, and bake for an additional 20 minutes until the top is golden brown and the sauce is bubbly.
