My favorite way to cook Brussels sprouts is to halve and roast them until they develop those delectable crispy outer leaves, then served with my essential lemon garlic sauce. I’ve been doing them that way (also, with small diced pork belly added to the pan) for years.
What is Au Gratin?
This winter, I thought I’d try a new technique: au gratin– where you partially roast the Brussels sprouts then finish them inside of a light and cheesy béchamel sauce.
So, technically, an au gratin is either cheese or breadcrumbs plus baking. BUT. The sauce part is a nice touch and is totally easy. You’ll see.
Brussels sprouts love cheese, especially hard cheese — so much flavor!
For the cheese part, I tried a combination of parmesan and gruyere, and you know what? While the cheese added a nuttiness, overall, these winter sprouts were on the sweet side of savory. Actually, I went overboard with caramelizing the onion. Just a cautionary tale.
Sweat the Onion for a Savory Flavor
My goal was to sweat the onion until soft and avoid any browning. Since I minced the shallots, they caramelized so quickly! I’ve included a good note in the recipe to ensure your dish comes out more on the savory side.
Another thing. I wanted desperately to use fresh thyme in this recipe because it really compliments Brussels sprouts, but they were sold out. Go figure. I tried fresh marjoram, instead. Big mistake. It totally overpowered the flavor–I don’t recommend it.
If, however, you can’t find fresh thyme, I think parsley or even lemon zest would make a better substitute.
All of this is to say, if you are looking for a good Brussels sprouts au gratin recipe, this is it! It comes together really quickly and would make a lovely side dish to some turkey. Just take my advice, and don’t caramelize the onion (that is, unless you are a big fan of sweet flavors).
Let me know what you think! Feel free to drop any additions or subtractions in the comments below.
P.S. This Irish Soda Bread.
P.S.S. Your Winter Produce Guide
BRUSSELS SPROUTS AU GRATIN
- 2 pounds Brussels sprouts ends trimmed and halved
- 1/2 teaspoon sea salt
- 2 tablespoons extra virgin olive oil
- 2 large shallots (about 1/3 cup) minced
- 1 tablespoon ghee or butter or olive oil
- 2 teaspoons all-purpose flour
- 1 1/4 cup whole milk or reduced fat milk
- 1/4 teaspoon salt
- 1 tablespoon fresh thyme leaves
- 2 tablespoons grated parmesan cheese
- 2 ounces grated gruyere
- Preheat oven to 400°F. In a large bowl, toss the Brussels sprouts with olive oil and salt until well-coated. Spread in a large baking dish (you want a shallow layer to get some browning) and roast for 25 minutes.
- Meanwhile, in a large pan over low heat, melt the ghee and sweat the shallots just until aromatic and tender, about 2 minutes (avoid browning the onion or it will cause the final dish to have a sweet taste). Add the flour and stir just to coat the onion. Immediately add the milk, salt, thyme, and cheeses. Stir and cook just until slightly thickened (raise the heat to medium to achieve this quicker).
- Pour the sauce over the pre-roasted Brussels sprouts and return the dish to the oven for 15 minutes. To serve, top with more parmesan cheese and enjoy while it's hot.