Mom’s Au Gratin Potatoes
Time: 60 minutes
2 kinds of potatoes (I like yellow & russet), washed & dried, about 6 of each kind
Shredded cheddar, the sharper the better, about 2.5 cups (about 200 g)
Note: My mom likes to mix her cheeses and she often uses Colby & Monterey Jack. I live in Italy and cheddar is the only cheese I can get that works in this dish. Pecorino, gouda, scamorza, mozzarella, parmigiano - they all fail, so don’t even bother. They simply do not melt properly or taste quite right. So… If you have access to Colby or Monterey Jack, go for it! If not, just use cheddar.
Heavy whipping cream, 1 pint or 500 mL
Flour (about 3 T) (about 50 grams)
Salter butter (250 g or 2 sticks)
Salt and pepper, generous, to taste
Oregano (trust me!), about 2 T (30 g)
Preheat your oven to 375 degrees fahrenheit or 200 degrees celsius.
Using a mandolin and cut-resistant kitchen gloves, carefully slice the potatoes to about 2-3 mm thickness (quarter inch). Set aside.
In a small saucepan, over medium heat, melt the salted butter. Make sure it doesn’t brown - turn the heat down if it starts bubbling too quickly!
In a seamless fashion, begin stirring in the flour until it forms a sort of chunky dough-like substance. This is a crucial step!
Slowly, add the heaving whipping cream and cook, whisking constantly, until the mixture begins to thicken.
As you whisk, if you start to feel a bit of resistance with your whisk, add 2 cups of the shredded cheddar.
(If you add the cheddar too soon, the bechamel struggles to thicken).
Keep whisking while you add salt, pepper, and oregano (to taste).
Why oregano? This version of au gratin potatoes calls for oregano because I have found that cheese and milk and potatoes all have a similar flavor profile when baked. Adding just a tad of oregano changes this ever-so-slightly, and just brings something extra special to the table. Trust me!
If the mixture is not thick enough, resist the temptation to add more flour!
Why? Flour changes the flavor of sauces subtly. To thicken without changing flavor, add cornstarch instead, by small spoonfuls at a time, until incorporated fully. The cornstarch will help it reach the desired consistency without altering the flavor.
I usually need to add 1-2 spoonfuls of cornstarch to get the sauce as thick as I like it.
(Yes, this is a variation on a bechamel using cheddar and chemistry!)
Lay the potato slices in one layer inside a buttered 9x13 baking dish (should be made of glass for proper/uniform heating).
Drizzle some of the cheddar sauce over the potatoes.
Layer potatoes on top, and then add more sauce. You can do this one more time probably, until all the materials have been used.
Lightly tent the pan with aluminum foil and place it, carefully, into the heated oven.
Bake for about 40 minutes. Then, remove the foil and add another ½ cup of shredded cheddar cheese on top.
Bake for another 5-15 minutes, depending on: how hot your oven is, how thick your potato slices are, how soft you like your potatoes to feel, etc. If it is bubbly and a bit browned on top, it is done, but feel free to stick a knife in it to double check. The knife should glide right through the potatoes with ease...
Cool for about 5-10 minutes before serving, with the foil back on. This helps the flavors to meld.
Note: This can be prepared in advance! Simply follow steps 2-11, place the pan in the fridge overnight, and bake it the next day. I often do this for holidays when counter space and oven time are precious.