While researching recipes, I couldn't believe the variation. Some people parboil their sliced potatoes before baking them, and some use them raw; some people put cheese between each layer of potatoes, some only put it on top, some make a cheese sauce, and some don't use cheese at all (I don't quite understand that last one). Cheddar or gruyere? Heavy cream or whole milk? Would you like to add onions, turnips, or go pure potato? Choices, choices!
Since it was obvious that there was no set formula to follow, I figured that I couldn't possibly mess up that much; so, I decided to wing it. I sauteed sliced onions and cremini mushrooms with some chopped garlic in olive oil, and fried and crumbled a few slices of bacon. Then, I layered this mixture with the potato slices in a buttered baking dish.
To some heavy cream, I added kosher salt, freshly cracked pepper, and, since I love what it does to alfedo sauce, a little bit of ground nutmeg. I heated it to a simmer in a sauce pan to thicken it a bit, and poured it gently over the potatoes, until they were just covered.
I covered the dish with foil and baked it until the potatoes were cooked through; then, I added plenty of aged cheddar cheese and dried thyme on top before baking it uncovered.
Once it was beautifully browned, it was time for the hardest part: letting the dish rest before digging in.
As usual with labours of foodie love, it was worth the wait. Decadently creamy and full of flavour, the potatoes au gratin were just what I wanted on a cozy Sunday evening. They would make a great side dish to just about anything, but since we were eating them as a main dish, I served them with a simple salad. I'm so glad I made much more than I needed (I can't wait to eat them with tomorrow night's salmon!)
I think this dish is elegant enough to serve at a nice dinner party. A convenient bonus is that you could assemble the entire thing the day before, and just throw it in the oven while you get everything else ready. I know I'll be serving it with pride very soon!
Potatoes au Gratin with Onions, Mushrooms, and Bacon: The Recipe
3 lbs russet potatoes, peeled and sliced thinly
1 lb sliced cremini mushrooms
1 large onion, sliced
1 clove garlic, chopped
6 slices bacon, cooked and crumbled
3-4 cups heavy cream
kosher salt and freshly cracked black pepper, to taste
2 cups shredded aged cheddar
Preheat oven to 375C. Saute onions, mushrooms, and garlic in olive oil with kosher salt and fresh pepper, until softened. Place a layer of potato slices in the bottom of a buttered 9x13 in baking dish, overlapping slightly. Spread half of onion and mushroom mixture and half of bacon over the potatoes, top with another layer of potatoes; repeat.
Add kosher salt, fresh pepper, and nutmeg to the heavy cream; bring to a simmer. Pour over potatoes until just covered. Cover baking dish with foil, and bake for 40-45 minutes, or until potatoes are tender (pierce with a fork.) Remove foil and top with cheese, and sprinkle with thyme. Bake for another 30-35 minutes to brown. Broil for a few minutes, if desired. Let stand for 10-15 minutes before serving.