Ingredients:
3 lb Russet potatoes, peeled and sliced into 1/4 inch thick rounds
2 1/2 tablespoons butter
1 small bulb fennel, sliced into 1/4 inch thick half-moons
1 medium onion, sliced into 1/4 inch thick half-moons
2 cloves garlic, minced
1/3 cup flour
2 cups whole milk
1 cup chicken or vegetable stock
2 cups shredded Gruyère
1 cup shredded Gouda
salt
freshly ground black pepper
fennel fronds, as garnish (optional)

Directions:
Preheat oven to 355. Lightly oil an 2 1/2 quart baking dish. Set aside.

Place the potatoes in a large bowl of cool water. Allow to soak 10-15 minutes. Drain and let air dry.

Meanwhile, in a large saucepan, saute the fennel, garlic, and onion until the onion is soft and translucent. Do not brown. Add the flour and whisk to coat the vegetables. Add the milk and stock and bring to a simmer. Stir in 1 3/4 cup Gruyère, 3/4 cup Gouda, salt and pepper and cook, stirring continuously until the mixture thickens.

Arrange half of the potatoes in the prepared baking dish. Pour half of the cheese mixture over the potatoes. Top with remaining potatoes. Pour the remaining sauce over the potatoes. Sprinkle with remaining shredded cheese and fennel fronds.

Bake, uncovered for 1 hour or until the potatoes are fork-tender and the dish is browned and bubbly*. Allow sitting 5-10 minutes prior to serving. Refrigerate leftovers.

*This dish is very bubbly so you may want to line your oven (I use this oven liner or you could use foil) or place the baking dish on a baking sheet to avoid dripping directly onto the oven.

My thoughts:

I always get asked what is the difference is between au Gratin potatoes and scalloped potatoes. The answer is easy: au Gratin is topped with a sprinkle of  cheese (or bread crumbs) and scalloped is not. I do see a lot of scalloped potato recipes with cheese in them which I think is a reflection of our country’s urge to put cheese in and on everything and everywhere. Now I think the names are pretty much used interchangeably but I do tend to use au Gratin as it was originally intended because in my mind, scalloped potatoes are quite different.

I’ve been shopping at Aldi lately because not only is it cheap, they have a lot of European foods  that are tricky (or costly) to find else where. I was delighted to see that they are now carrying Gruyère and Gouda right next to the usual shredded cheddar and mozzarella and it wasn’t even a special sale. Plus I think it was only about $2.50 for 8 oz which is a great deal for both cheeses and I didn’t have to shred an unwieldy wheel of Gouda myself. Score! They are both great cheeses to use for au Gratin potatoes because they melt wonderfully, they have distinctive but not overpowering flavors and they seem a little fancier than regular old cheddar. If I am going to go through the hassle of making a cheese sauce and slicing all those potatoes on a Tuesday night I want it to seem special! It also makes the dish holiday-worthy, I think.

This is a rich, creamy dish, I admit but I lightened it up a bit by using 1/3 stock for the liquid rather than 100% milk. I think it adds a bit more flavor to the finished dish and I don’t know if I am imagining this but I never have problems with re-heating the dish the next day; the sauce doesn’t split at all. I hate when you reheat dishes (even from restaurants!) like this and it gets all oily or clotted looking but that didn’t happen with this at all, which is awesome because this recipe makes a ton and you are bound to have some leftovers.