Creamy Fennel Gratin

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Creamy fennel gratin is a cozy vegetable side dish with thinly sliced fennel baked in a garlic-scented cream sauce and finished with a buttery Parmesan breadcrumb topping. The fennel softens in the cream until tender but not mushy, while the topping turns golden and crisp for just the right contrast.

And if you’re not a fan of licorice, don’t let that scare you away from fennel. I am not a fan of licorice myself, but I love fennel when it’s cooked like this. The flavor mellows as it bakes, becoming lightly sweet and savory, with just enough texture.

This gratin feels elegant enough for a holiday meal, but it’s simple enough for a weekend dinner with roast chicken, pork, beef, or seafood. I especially like that it gives you the creamy comfort of a gratin without being quite as heavy as a potato version.

What I Love About This Recipe

• The flavor and texture of the fennel. Raw fennel has a distinctive anise flavor and crisp texture. When cooked with the cream, it becomes softer with a more delicate flavor. You can still taste the fennel, but it is gentle, and it works beautifully in the creamy sauce.
• The creamy sauce is simple yet flavorful. Heavy cream, a little dry white wine, grated garlic, and a dash of nutmeg bring brightness, warmth, and savory depth.
• Nice alternative to potato gratin. You get the same creamy filling, but the fennel makes it feel lighter and even a bit unexpected.
• The topping adds texture to the dish. Fresh buttery breadcrumbs and Parmesan cheese bake into a crunchy golden topping over the soft fennel filling.

Ingredient Notes

• Fennel – Look for large, firm fennel bulbs with smooth white layers and fresh-looking fronds if possible. The fronds make a pretty garnish, so save a few before trimming the bulbs. Cutting out the small woody core helps the slices separate and become tender.
• Heavy cream – Cream gives the gratin its rich texture and helps the fennel bake into a tender, silky layer. Since the sauce is simple, heavy cream works best here and gives the dish the right body. It also stands up to the heat better than milk and is less likely to separate or curdle as the gratin bakes.
• Dry white wine – Adds a touch of acidity and helps balance the rich creaminess. You can substitute chicken or vegetable broth or water if you prefer not to use wine.
• Seasonings – Garlic, nutmeg, salt, and pepper provide the seasoning. Grating the garlic ensures it distributes quickly and flavors the sauce without leaving large pieces. Make sure to taste the sauce before baking.
• Fresh breadcrumbs – They give the topping a crisp-tender texture. I like coarse crumbs for the topping. I pulse them in the food processor and sift the finer crumbs into a bowl, leaving perfect coarse crumbs. The fine crumbs can be frozen and used in meatloaf, meatballs, and finer coatings.
• Parmesan cheese – Adds a nutty, somewhat salty flavor to the topping and helps it brown. Grate it with a zester or shred it on the smallest holes of a box grater.

Steps to Make Fennel Gratin

1. Prepare the baking dish and trim and slice the fennel bulbs by removing the stalks, root ends, and cores.
2. Simmer the sliced fennel, cream, wine, and seasonings on the stovetop for a few minutes to soften it slightly.
3. In a small bowl, combine the breadcrumbs with the Parmesan cheese, melted butter, and thyme leaves, if using. Set aside.
4. Transfer the fennel to the baking dish with a slotted spoon. Pour the cream mixture over it until it nearly reaches the top of the fennel. It shouldn’t cover the fennel. You may have a little extra cream left over.
5. Bake the fennel in the cream mixture for about 20 minutes, then top it with the breadcrumbs and bake until the topping is golden brown and the fennel is tender yet not mushy.
6. Let the gratin rest for 10 minutes before serving. Garnish with fennel fronds and chives if you like.

Fennel Gratin Tips

• Slice the fennel evenly so all the pieces cook at the same pace. Very thick slices may stay too firm, while very thin slices will soften more quickly.
• Simmer gently after the cream comes to temperature. A hard boil can reduce the cream too quickly or make it more likely to separate.
• Season the cream mixture before transferring it to the baking dish. Fennel and cream both need enough salt to taste balanced, and it’s easier to adjust the seasoning before the gratin is assembled.
• Add only enough cream mixture to come nearly to the top of the fennel. If the fennel is completely submerged, the gratin may turn out looser and the topping won’t have as much contrast with the filling.
• Rest the gratin before serving. It will still be hot, but the sauce will be slightly thicker and the portions will hold together better.

Recipe Variations

• Add more cheese. Add 1/2 cup of Gruyère, fontina, or mild white cheddar to the fennel before baking or sprinkle some under the breadcrumb topping. Gruyère is especially good with fennel because it melts well and adds a nutty, savory flavor.
• Add sliced shallots. Thinly sliced shallots can be cooked with the fennel for extra sweetness. They blend nicely into the cream sauce and make the gratin taste a little more layered.
• Add a lemony finish. A small amount of lemon zest in the breadcrumb topping or a light squeeze of lemon before serving can brighten the cream and fennel. This variation is especially nice if you’re serving the gratin with fish or seafood.

How to Serve the Dish

• Pair it with beef tenderloin, prime rib, or pot roast for a holiday or Sunday dinner. The rich cream sauce works well with beef, while the fennel keeps the side dish from tasting too heavy.
• Choose fish or seafood for a lighter pairing. Fennel is a natural match for seafood, and the creamy gratin makes baked fish, seared scallops, or shrimp feel like a complete meal.
• Serve it as part of a holiday side dish spread with roasted carrots, green beans, mashed potatoes, dressing, or rolls. It brings a different flavor to the table without competing with the traditional favorites.

How to Store

• Refrigerate: Store leftover fennel gratin in an airtight container or cover the baking dish tightly and refrigerate it for up to 3 to 4 days. Let it cool before covering, but don’t leave it at room temperature for more than 2 hours.
• Reheat: Reheat the gratin in a covered baking dish in a 350°F oven for 10 to 20 minutes or until hot throughout, then uncover it for the last few minutes to help the topping crisp again. Individual portions can be reheated in the microwave, but the breadcrumb topping will be softer.
• Freeze: Freezing is not recommended because the cream sauce may separate, and the fennel can release extra liquid when thawed. If you do freeze it, wrap it tightly, freeze for up to 1 month, thaw overnight in the refrigerator, and reheat gently.