Step 1

Preheat the oven to 375°F.

Step 2

Slice potatoes into 1/4 inch thick rounds and layer flat in a large skillet. (I like to use a mandoline to get the slices as even as possible.)

Step 3

In a saucepan, on medium-low heat, melt butter and add the flour to make a roux. Whisk constantly for 5 minutes.

Step 4

As the roux gets darker, slowly add buttermilk, whisking as you pour.

Step 5

Add ranch seasoning, black pepper, and salt. Remove from heat.

Step 6

Stir in 1 cup shredded cheese (I like to switch to a spatula instead of whisk), making sure it is melted.

Step 7

Pour the cheese sauce over the potatoes that are in the skillet.

Step 8

Cover the skillet and cook for about an hour.

Step 9

Uncover the potatoes, add the second cup of cheese, and bake for 25-30 more minutes, or until the cheese is browned.