Au Gratin Potatoes.

You can cook Au Gratin Potatoes using 9 ingredients and 8 steps. Here is how you achieve it.

Ingredients of Au Gratin Potatoes

1. It’s 4 of Russet Potatoes cut apx. 1/4 in thick.
2. Prepare 1 of yellow onion slices into half rings.
3. It’s 1/2 stick of butter.
4. It’s 1/2 tsp of salt.
5. Prepare 1 tsp of garlic powder.
6. You need 3 TBS of flower.
7. Prepare 2 cups of milk.
8. Prepare 1 of small bag shredded triple cheddar cheese.
9. It’s 1 cup of parmesan cheese.

Au Gratin Potatoes step by step

1. Preheat oven to 400 degrees F and butter a 9×13 glass baking dish..
2. In a medium-size pot, melt butter over medium heat. Mix in the flour, garlic powder, and salt. Stir constantly for one minute..
3. Stir in milk. Cook until mixture has thickened..
4. Stir in cheese all at once, and continue stirring until melted, about 30 to 60 seconds..
5. Layer 1/2 of the potatoes into bottom of the prepared casserole dish and top with the onion slices. Then pour half the cheese mixture on top..
6. Repeat step 5 with remaining potatoes, onions, and cheese mixture..
7. Cover with aluminum foil and place in oven for 1 hour. Remove foil and bake for an additional 30 minutes. (Or longer if you desire a crisper finish.).
8. Set aside to rest for 15 min then it's ready to serve..