Saturday Night Date Night In (And a potatoes au gratin recipe)

Instead of going out tonight, Guinea Pig and I decided to stay in and have a nice dinner here instead. I took the money we would have normally spent on a night out and had filet mignon with a Merlot Balsamic reduction, garlic steamed broccoli, and (I decided to spoil him) potatoes au gratin, which stole the show. My steak was a bit overdone (Guinea Pig liked his), and the broccoli was just okay, but I had to share this potato au gratin recipe! I got another 10 out of 10! Wah hoo! 

Ingredients

• 5 potatoes, sliced on the mandolin
• 1 large yellow onion (I also sliced this on the mandolin)
• 4 Tbsp butter divided
• 1 Tbsp flour
• Salt
• Black pepper
• 1/2 teaspoon nutmeg
• 1 cup (packed) grated Gruyere cheese (about 4 oz)
• 8 Tbsp (packed) freshly grated Parmesan cheese (about 2 oz)
• 2/3 cup 1% milk
• Panko crumbs

Directions

Preheat oven to 400°F.

1 Boil the potatoes for 4 minutes in salted water. Drain and set aside.
2 Heat the butter over medium-high heat in a large sauté pan and cook the onions, stirring occasionally, until they are softened, about 5 minutes. Sprinkle them with salt, remove from heat, and set aside.
3 Spread half of the sliced potatoes over the bottom of a baking dish (I used 8 1/2 x 11). Sprinkle well with salt and pepper. Sprinkle a bit of the Gruyure and Parmesan cheeses. Top with the onions.
4 In another pan, heat 1-2T of butter. Once that is melted, stir in the flour  (as an aside, I think other herbs could work well here!) and make a roux. (Be careful not to burn the flour! I've done this too many times and it is not a quick fix!) Once the roux is brown and thickened, add the milk and stir quickly. Boil the mixture and then add the cheeses (save a little bit for the top) and nutmeg.   
5 Add the rest of the potatoes over the onions in the pan and pour the cheese mixture over all of the potatoes.
6 Sprinkle the remaining cheese over the potatoes.
7 Liberally sprinkle Panko crumbs over the top.
8 Bake uncovered in 400°F oven until cream thickens and everything is nicely browned, about 25-30 minutes.

Adapted from: http://simplyrecipes.com/recipes/onion_potato_gratin/