Brussels Sprouts Gratin with Blue Cheese is a creamy, savory side dish with tender sprouts, tangy blue cheese, whole-grain mustard, and a golden Parmesan topping. It comes together in about 40 minutes and works beautifully for holiday dinners or cozy family meals.
If you want Brussels sprouts to feel a little more special than a simple roasted side, this gratin is a great choice. The sprouts keep just enough bite while baking in a rich cream sauce, so the finished dish feels comforting without losing the character of the vegetables.
Blue cheese provides the strongest flavor in the dish, while Parmesan adds a salty, golden finish. Whole-grain mustard cuts through the richness of the cream and milk and gives the sauce a subtle tang that works particularly well with Brussels sprouts.
It is also straightforward to prepare. Briefly boiling the sprouts gives them a head start, and after that, most of the work happens in the oven. That makes this creamy Brussels sprouts gratin especially practical when you are already preparing several dishes for the same meal.
Brussels Sprouts Gratin Ingredients
You only need a small collection of ingredients for this gratin, but each one has an important job in creating the creamy texture and bold, savory flavor.
- Brussels sprouts: Halving the sprouts lengthwise helps them cook evenly while still keeping some structure after baking.
- Blue cheese: Crumbled blue cheese melts into the cream mixture and provides the distinctive tangy, savory character of the gratin.
- Heavy cream: Creates the rich base of the sauce and helps give the finished dish its smooth consistency.
- Whole milk: Lightens the heavy cream slightly while still keeping the sauce creamy.
- Whole-grain mustard: Adds gentle acidity and a subtle mustard flavor that balances the richness of the dairy and cheese.
- Parmesan cheese: Forms the salty, lightly browned layer across the surface of the gratin.
- Unsalted butter: Used to grease the baking dish, helping prevent sticking while adding a little extra richness around the edges.
- Salt and black pepper: Bring the flavors together and can be adjusted depending on the saltiness of your cheeses.
How to Make This Brussels Sprouts Gratin
STEP 1: Heat your oven to 350°F. Coat a shallow baking dish thoroughly with the butter, making sure the bottom and sides are lightly covered so the creamy gratin releases easily after baking.
STEP 2: Bring a medium saucepan of well-salted water to a boil. Add the halved Brussels sprouts and cook them for about 3 minutes. You are only partially cooking them at this stage, so they should soften slightly without becoming completely tender.
STEP 3: Drain the Brussels sprouts very well. Pat them dry with a clean kitchen towel or paper towels before transferring them to the baking dish. Removing surface moisture is important because excess water can thin the cream sauce.
STEP 4: Arrange the Brussels sprouts in an even layer in your prepared dish. Scatter the crumbled blue cheese over and between the sprouts so you get pockets of cheese throughout rather than concentrating it in one area.
STEP 5: Whisk together the heavy cream, whole milk, and whole-grain mustard in a small bowl. Add black pepper and a modest amount of salt. Remember that both blue cheese and Parmesan are naturally salty, so it is better to season conservatively at first.
STEP 6: Pour the cream mixture slowly and evenly over the Brussels sprouts. Give the baking dish a gentle tap against the counter so some of the liquid settles into the gaps around the vegetables and cheese.
STEP 7: Finish by scattering the freshly grated Parmesan over the surface. Bake for 20 to 25 minutes, until the cream is bubbling around the edges and the Parmesan has developed an appetizing golden finish. Let the gratin rest for several minutes before serving so the sauce can settle slightly.
Serving Ideas for Brussels Sprouts Gratin
Because this side dish is rich and creamy, it pairs particularly well with simply prepared main courses that will not compete with the blue cheese.
- Roasted chicken or turkey: The savory poultry balances the tangy cheese sauce, making this an excellent option for Thanksgiving, Christmas, or a Sunday dinner.
- Roast beef or steak: Brussels sprouts and blue cheese are both natural partners for beef, especially when the meat is simply seasoned.
- Baked ham: The salty-sweet character of ham works nicely alongside the creamy mustard and cheese flavors in the gratin.
You can serve the gratin directly from its baking dish while it is still warm. Give it those few minutes of resting time first, though, since the cream sauce will be easier to spoon once it has had a chance to settle.
Can I prepare Brussels sprouts gratin ahead of time?
Yes. You can blanch and dry the Brussels sprouts several hours ahead and keep them refrigerated. You can also assemble the gratin in advance, cover it, and refrigerate it until closer to baking time. If the dish is very cold, it may need a few additional minutes in the oven.
Why should I dry the Brussels sprouts after boiling?
Drying them prevents extra water from diluting the cream and milk mixture. Brussels sprouts can hold quite a bit of moisture after blanching, so draining and patting them dry helps produce a richer, more concentrated sauce rather than a watery gratin.
Can I use less blue cheese?
You can reduce the amount slightly if you prefer a milder blue cheese flavor, but keep in mind that it is one of the main flavor components of the dish. Parmesan will still provide saltiness and richness, while the mustard helps keep the sauce balanced.
How do I know when the gratin is finished baking?
Look for steady bubbling around the sides of the baking dish and a golden surface. The Brussels sprouts should be tender when pierced but should not completely fall apart. The sauce may still look fairly fluid immediately after baking and will settle as the dish rests.
Can I make this without whole-grain mustard?
The mustard contributes tang and helps balance the cream and cheese, but the gratin can still be prepared without it. The final flavor will simply be richer and more cheese-forward. If you enjoy the gentle sharpness mustard provides, it is worth keeping in the dish.
Pro Tips for Brussels Sprouts Gratin
- Do not overcook the sprouts during boiling. Three minutes is enough to begin softening them. They will continue cooking for another 20 to 25 minutes in the oven.
- Season carefully. Blue cheese and Parmesan already contribute plenty of savory, salty flavor, so taste and season thoughtfully rather than adding a large amount of salt automatically.
- Let it rest before serving. Waiting several minutes after baking allows the creamy sauce to settle around the sprouts and makes portions easier to serve. A little freshly cracked black pepper over the top is a simple finishing touch.
Keeping Leftovers Fresh
Allow leftover gratin to cool before transferring it to a covered container. Store it in the refrigerator for up to 3 to 4 days.
For reheating, place individual portions in a microwave-safe dish and warm gently until heated through. For larger portions, cover the baking dish loosely and reheat in a 325°F to 350°F oven until the center is hot. Using moderate heat helps prevent the cream sauce from separating.
The gratin can technically be frozen for up to about 1 month, but freezing is not the preferred storage method. Cream-based sauces can become slightly grainy or separate after thawing, and the Brussels sprouts will usually become softer.
If you do freeze it, cool the gratin completely first and store it in an airtight freezer-safe container. Thaw overnight in the refrigerator, then reheat it gently in the oven. The texture may not be quite as smooth as when freshly baked, but the savory blue cheese and Brussels sprouts flavor will still come through.
Brussels Sprouts Gratin with Blue Cheese
Ingredients
- 6 oz crumbled blue cheese such as Maytag Blue
- 3/4 cup heavy cream
- 1 1/2 lb Brussels sprouts sliced in half lengthwise
- 1 tablespoon whole-grain mustard
- 1/4 cup freshly grated Parmesan cheese
- 1 teaspoon unsalted butter preferably Kerrygold for a fuller flavor
- 1/2 cup whole milk
- Salt and freshly ground black pepper as needed
Instructions
- Preheat the oven to 350°F. Use the butter to thoroughly grease a shallow baking dish, then set the prepared dish aside.
- Bring a medium saucepan of salted water to a rolling boil. Add the halved Brussels sprouts and boil for 3 minutes, allowing them to soften slightly without becoming fully tender.
- Drain the Brussels sprouts thoroughly, then pat them dry to eliminate as much excess moisture as possible.
- Spread the cooked Brussels sprouts evenly across the bottom of the buttered baking dish. Scatter the crumbled blue cheese uniformly over the sprouts so the cheese is distributed throughout the gratin.
- In a small bowl, whisk the heavy cream, whole milk, and whole-grain mustard together until well combined. Season the mixture with salt and black pepper according to taste.
- Pour the cream mixture evenly over the Brussels sprouts and blue cheese. Gently tap the baking dish against the countertop to help the liquid settle between the sprouts and mingle with the cheese.
- Sprinkle the grated Parmesan evenly across the entire surface.
- Place the baking dish in the preheated oven and bake for 20–25 minutes, or until the cream is visibly bubbling and the top has developed a golden-brown finish.
- Remove the gratin from the oven and allow it to rest for several minutes before serving. This brief resting period helps the sauce settle and makes the gratin easier to portion neatly.