Russets Vs. Reds: The Battle of the Spuds

So, here it is. I am including this recipe because I have had so many requests for it. I came by it over a very long and tedious process, but I am so happy with the results!
It all began many moons ago. I decided to try my hand at homemade au gratin potatoes. I LOVE au gratin potatoes, and, in accordance with my life motto, Everything must be better homemade! How could that little bag of powdery cheese, some dried potatoes, milk and butter taste better what was created at home?
I began trying different things. I put peeled, chopped russet potatoes, thinly sliced onions, minced garlic, whole milk, sour cream and plops of butter in a pan and baked it. After a very long time in the oven, it emerged. Good, but not what I wanted. Plus, I had to keep testing to see if the potatoes were done. Sometimes when I made it the potatoes were done, other times there were still some crunchy ones left.
I tried a cheese sauce, similar to the one I now use, but in the oven I still was left with potatoes that were not done, or, if they were done, it was an incredibly long, undetermined cooking time.
Another very disturbing factor was that I could not easily adjust the recipe. I am always cooking for a different amount of people and definitely do not like not being able to change amounts and cooking time with pretty standard results.

I had a huge fiasco one Easter. I had made my potatoes and they never finished cooking. They were way too crunchy, just gross, and I was mortified because everyone took one or two bites and left them on their plate. I wanted to apologize profusely, but I had just read that you are supposed to pretty much pretend like all the food tastes the way you want it to. I mean who wants someone to apologize all through the meal? It sounds like you are fishing for a compliment or something. And where do you draw the line? "I'm sorry, the rolls are not perfectly round and all the same size." "I'm sorry, this isn't as hot as I wanted it." "I'm sorry it took so long." "I'm sorry you don't like rice." "I'm sorry the cake is a little taller on one side." On and on and on...So I tried really hard not to do it. I just sat there and ate quietly, hoping for the meal to be over.
Then, I stumbled across this technique. I precooked the potatoes, made the sauce, assembled the two and popped them in the oven. This creamy, dreamy potato cheese ensemble is wonderful. The red potatoes retain their shape perfectly, and the sauce is surprisingly cheesy and oh so gooey. If you have cooked ham, dice it and throw it in with some broccoli and you have yourself a one meal deal! It can be done ahead of time and refrigerated, which makes it great for crowds or special occasions, and your potatoes are never, ever crunchy!

Au Gratin Potatoes

3 lbs red potatoes
6 tablespoons butter
1/4 cup flour, plus more as needed
1/4 teaspoon cayenne pepper
3 cups whole milk
1 cup chicken stock or broth
1 cup grated sharp white Cheddar
2 cups plus 1 cup grated sharp yellow Cheddar
salt and pepper to taste

Peel potatoes and chop them into 1/2 inch pieces. Bring a large pot of water to a boil and add the potatoes, reduce the heat to medium low, and allow to simmer for 15-20 minutes until done. Drain potatoes place in a 9x12 baking dish.
Preheat oven to 375.
Meanwhile, heat a medium sauce pan over medium-low heat. Add the butter and heat until it melts. Raise the heat a bit and whisk in the flour and cayenne pepper. Whisk until the roux bubbles up, then cook for 1 minute more. Whisk in the milk and stock and raise the heat a bit higher to bring the sauce to a quick boil. Once it bubbles, drop the heat back down to a simmer and cook until sauce thickens, 3 to 5 minutes.
Add the white Cheddar and 2 cups of the yellow Cheddar to the thickened sauce and stir to melt it, a minute or so. Add salt and pepper to taste. Pour sauce over potatoes and top with remaining cheese.
Place in oven to melt cheese and rewarm potatoes.