This brussels sprouts gratin with cheese sauce is based on Julia Child’s Choux de Bruxelles à la Mornay, Gratinés, and is a rich vegetable side dish made with homemade béchamel.
Do you ever buy brussels sprouts on the stalk?
I do, and recently I snagged three big stalks of brussels sprouts at Trader Joe’s!
Except guys, three stalks of brussels sprouts is a massive amount of sprouts.
Once I’d removed them from the stalk, there were way more sprouts than I expected. Oops.
Since I over-bought, we now get to eat brussels sprouts every day.
I don’t mind at all because I love this bitter veggie!
This week, though, I wanted something a little richer. I wanted comfort food.
I wanted Julia Child’s brussels sprouts gratin.
This recipe, like many of Julia’s recipes, might seem complicated at first, but each step is fairly simple. I recommend reading the recipe in full before beginning.
Julia Child’s Recipe
This recipe is based on Julia Child’s Choux de Bruxelles à la Mornay, Gratinés (brussels sprouts gratin with cheese sauce) from her book Mastering the Art of French Cooking, Volume I.
If you want to try Julia’s version from her book, keep in mind that you’ll need to visit, not one, but four recipes in her book, as the main recipe references three other recipes.
I’ve put everything in one place for you.
I did make a few small adaptions to Julia’s recipe (for simplicity).
Should I Blanch the Brussels Sprouts Before Roasting?
You can, but you don’t have to.
Julia recommends it, but I prefer to skip this step.
I think they pick up more sweet notes in the oven without blanching. That said, blanching will make your sprouts a little more tender.
Do whichever you prefer.
Do I Have to Remove the Outer Leaves of the Brussels Sprouts?
If any leaves appear damaged or dirty, then yes of course, remove them. Otherwise, I simply remove the tough stem area and halve or quarter the sprouts.
Should I Roast the Brussels Sprouts in Oil or Butter?
Julia calls for roasting the sprouts in melted butter.
As a (slightly) quicker alternative, I prefer to use olive oil. It saves a little time and there is still plenty of butter in this recipe.
How to Roast the Brussels Sprouts
Start with your prepared sprouts, and then toss them in oil or butter and a little sea salt.
Roast the brussels sprouts until they’re bright green and almost tender.
How to Make the Béchamel Sauce
If the term béchamel sounds intimidating, don’t worry.
Start with a heavy bottomed pan (if possible). I used this Lodge Enameled Cast Iron Dutch Oven.
Melt butter over low heat, and then begin stirring or whisking in some flour. If you’re avoiding gluten, gluten-free all purpose flour (such as Cup 4 Cup) will work perfectly.
Continue stirring until the butter and flour begin to foam.
Next, stir in hot milk.
Stir, stir, stir to incorporate the milk.
Bring the milk to a boil, boil for one minute, and then turn off the heat.
Next, stir in some cheese.
You can use Swiss or Parmesan, whichever you prefer or have on hand.
Season the béchamel with salt, cayenne, and nutmeg.
Make sure to taste the sauce at this point and adjust the seasoning. If it seems bland now, it will seem bland after cooking too.
Make the Brussels Sprout Gratin
Toss the roasted brussels sprouts in half the sauce, and then pour the rest of the sauce over the sprouts.
Top the entire dish with more cheese. Dot with butter.
Slide the casserole dish under your oven’s broiler and cook until the cheese is bubbly and golden.
Serve right away, along with some crusty bread and a glass of crisp white wine.
Brussels Sprouts Gratin
- medium casserole dish (9"x9" or 10"x10")
- heavy-bottomed pan
- 1 ½ pounds brussels sprouts, stems removed + sprouts halved or quartered
- 2 tablespoons olive oil Or swap 2 TB melted butter
- ¼ teaspoon sea salt
- 2 cups milk
- 3 tablespoons butter, divided
- 2 tablespoons flour Use AP gluten-free flour if needed
- ½ cup freshly grated Swiss (esp. Gruyere) or Parmesan cheese, divided Or use a mixture of both cheeses
- ¼ teaspoon sea salt
- ¼ teaspoon ground cayenne
- ¼ teaspoon freshly ground nutmeg
- Preheat oven to 425°F.Toss brussels sprouts with olive oil and sea salt. Arrange in a medium casserole dish (9×9 or 10×10), and bake 14-15 minutes, or until the sprouts have just turned bright green.
- While sprouts cook, make the béchamel sauce.Bring the milk to a boil in a saucepan. Alternatively, microwave the milk until it begins to simmer.Heat 2 tablespoons butter in a heavy bottomed pan over low heat. When the butter melts, stir in the flour. Continue stirring until the flour is incorporated with the butter and they begin to foam (but not brown). Allow the mixture to foam for 2 minutes.Begin slowly pouring in the hot milk, stirring or whisking constantly. The milk should be very hot (almost at boiling) when you pour it into the butter and flour.Bring the mixture to a boil and continue to boil for 1 minute. Turn off the heat.
- Stir ¼ cup of the cheese into the béchamel, and continue stirring until the cheese is melted.Add the sea salt, cayenne, and nutmeg. Stir again, and then taste. Add more seasoning if desired.
- When the sprouts are done roasting, fold half the sauce into the sprouts and stir.Pour the remaining sauce over the sprouts. Top with the remaining cheese.Cut the remaining butter into small cubes and dot the top.
- Move an oven rack to the position closest to the broiler.Position the casserole dish under the broiler and broil 3-5 minutes, or until the cheese is golden and bubbling.Serve immediately.
- Prepare the raw brussels sprouts by trimming and halving (or quartering) and store in the fridge for up to two days.
- Prepare the béchamel sauce up to three days ahead and store in the fridge. Reheat over low heat, adding more hot milk if needed.
- My sauce is lumpy: If the milk is still almost boiling when added and if you stir or whisk vigorously, there shouldn’t be lumps. If there are, you can purée the sauce in a blender.
- The sauce is too thick: With the heat on, whisk a little more hot milk back into the sauce. (Gluten-free AP flour will sometimes thicken the sauce more than intended.) Note that extra-thick sauce will work fine in this recipe, just make sure to spread it out evenly over the sprouts.