PERFECT Au Gratin Potatoes

Step 1

Preheat the oven to 350 degrees F.

Step 2

Melt the butter in a stock pot over medium-high heat. Add the flour and whisk until smooth. Simmer, whisking constantly, for 2 minutes. Add the onions and garlic and stir to combine. Add the milk, cream and salt and whisk until smooth. Bring to a simmer and whisk until thickened. Whisk in the Cheddar and half of the Parmesan cheese. Whisk until melted. Stir in the potatoes.

Step 3

Pour the potato mixture into a 2 quart casserole dish. Sprinkle with remaining Parmesan cheese.

Step 4

Cover with foil and bake for 1 hour or until the potatoes are soft. Remove foil and bake for another 20 minutes or until the top is lightly browned. Let sit for 5 minutes before serving.