3 Tbs butter
5 cloves garlic, minced
3 Tbs flour
2 cups milk
1 cup chicken broth
1 tsp sea salt
1/2 tsp onion powder
4 lbs Yukon gold potatoes, sliced thin (peeled if desired)
2 cups shredded sharp cheddar cheese
2 Tbs parmesan cheese
Make roux. Melt butter and add garlic. cook for 1 minute. Stir in flour and cook for 2 minutes. Slowly stir in milk and broth. Add sea salt, onion powder, and pepper. Let simmer, stirring every few minutes, for 5 minutes, or until thickened. Add 3/4 cup cheese and stir to melt in.
Peel, if desired, and slice potatoes. The thinner the better.
Add potatoes to greased 13×9 pan. Layer half the potatoes. Pour over half the cheese sauce. Layer other half of potatoes. Pour over rest of sauce. Sprinkle on the remaining cheddar cheese and the parmesan cheese.
Cover with foil and bake at400F for 30 minutes. Remove foil and bake uncovered for another 30 minutes.