Delicious Baked Kohlrabi Gratin

I had never even heard of kohlrabi until I spotted it at the farmers market last spring. Growing up, our veggie rotation stuck to the basics – carrots, peas, and the occasional broccoli. When I finally brought one home, it sat on my counter for days while I googled what to do with it.

That’s when I discovered that kohlrabi isn’t as complicated as it looks. Like many vegetables, it really shines when you keep things simple and let it do its thing. This gratin recipe has become my go-to way to prepare it – just a handful of ingredients, some basic prep work, and the oven does the rest.

What Kind of Kohlrabi Should I Use?

When shopping for kohlrabi, look for bulbs that are about 3-4 inches in diameter – these tend to be the most tender and sweet, while larger ones can become woody and tough. Both green and purple varieties work equally well in this gratin, since you’ll be peeling away the colored skin anyway. The flesh inside is always pale green to white, regardless of the outer color. For the best results, choose kohlrabi that feels heavy for its size and has crisp, fresh-looking leaves (if still attached). Just remember to peel your kohlrabi thoroughly, removing not just the outer skin but also the tough layer underneath until you reach the tender flesh.

Options for Substitutions

Need to make some swaps? Here are some helpful substitutions for this gratin recipe:

• Kohlrabi: If you can’t find kohlrabi, try using turnips, rutabaga, or even cauliflower. Just make sure to slice them thinly like the kohlrabi for even cooking.
• Leek: No leeks? Use a medium onion or 2-3 shallots instead. Just cook them a bit longer to get that nice, soft texture.
• Gruyère cheese: Swiss cheese makes a great alternative to Gruyère, or try a mix of sharp cheddar and Parmesan for a different but tasty flavor profile.
• Low-fat milk: You can use whole milk, half-and-half, or even a mix of milk and cream. For a non-dairy option, unsweetened plain almond milk works too, but the sauce might be slightly less creamy.
• Whole-wheat breadcrumbs: Regular breadcrumbs work fine, or try crushed crackers, crushed cornflakes, or ground almonds for a different crunchy topping.
• All-purpose flour: For a gluten-free version, use rice flour or cornstarch (use 2 tablespoons instead of 3).

Watch Out for These Mistakes While Cooking

The biggest challenge when making kohlrabi gratin is getting the vegetable slices just right – cutting them too thick will result in undercooked, crunchy pieces that won’t blend well with the creamy sauce, so aim for consistent 1/8-inch thickness using a sharp knife or mandoline.

Another common mistake is not cooking the flour long enough when making the sauce – make sure to cook it with the butter for at least 1-2 minutes to avoid a raw flour taste, and whisk constantly while adding the milk to prevent lumps from forming.

The gratin can quickly go from perfectly golden to burnt due to the cheese topping, so keep a close eye during the final 5-10 minutes of baking and cover with foil if the top is browning too quickly while the kohlrabi still needs more time to become tender.

For extra flavor and better texture, try salting the kohlrabi slices and letting them sit for 15 minutes before patting them dry – this helps remove excess moisture and ensures a creamy rather than watery gratin.

What to Serve With Kohlrabi Gratin?

This rich and creamy kohlrabi gratin makes a fantastic side dish, but it’s also hearty enough to be the star of your meal. If you’re serving it as a main course, pair it with a crisp green salad dressed with a light vinaigrette to balance out the richness of the gratin. For a complete meal, add some simple roasted chicken or grilled fish – the mild, nutty flavors of the kohlrabi work really well with both. Since this dish is on the heavier side, I like to keep the accompaniments pretty simple and light, letting the gratin’s cheesy goodness be the highlight of the plate.

Storage Instructions

Keep Fresh: This cozy kohlrabi gratin will stay good in the fridge for up to 3 days when stored in an airtight container. The creamy sauce might thicken up a bit in the fridge, but don’t worry – that’s totally normal!

Make Ahead: You can prep this gratin up to 24 hours in advance! Just assemble everything but hold off on the final baking step. Cover it well and keep it in the fridge, then pop it in the oven when you’re ready to serve. You might need to add an extra 5-10 minutes to the baking time if it’s coming straight from the fridge.

Reheat: To warm up leftover gratin, cover it with foil and heat in a 350°F oven for about 20 minutes, or until heated through. The microwave works too, but the oven helps keep that nice crispy top layer. Just heat in short intervals, stirring gently between each one.

Preparation Time	15-20 minutes
Cooking Time	30-35 minutes
Total Time	45-55 minutes
Level of Difficulty	Medium

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 1200-1400
• Protein: 45-55 g
• Fat: 60-70 g
• Carbohydrates: 130-150 g

Ingredients

For the casserole base:

• 3 lb kohlrabi (peeled and sliced into 1/8-inch rounds)

For the sautéed leek:

• 1 large leek (thinly sliced)
• 1 tbsp butter

For the creamy mixture:

• Pinch freshly grated nutmeg (for best aroma)
• 3 tbsp all-purpose flour (I always use King Arthur all-purpose flour)
• 1/2 tsp salt (fine sea salt is best)
• 1/4 tsp ground black pepper
• 1/3 cup low-fat milk
• 1 cup low-fat milk

For assembly and topping:

• 1/3 cup whole-wheat breadcrumbs (toasted for extra crunch)
• 1 cup gruyère cheese (shredded, about 4 oz)

Step 1: Prepare the Baking Dish and Cook Kohlrabi

• 3 lb kohlrabi (about 6 to 7 medium bulbs), peeled and sliced into 1/8-inch rounds
• Cooking spray

Preheat your oven to 400°F (200°C).

Bring a large pot of water to a boil.

Coat an 8-inch-square baking dish with cooking spray to prevent sticking.

Add the peeled and sliced kohlrabi to the boiling water and cook until tender, about 10 minutes.

Drain the cooked kohlrabi and set aside.

Step 2: Sauté the Leek

• 2 tablespoons butter
• 1 large leek, white and light green parts only, thinly sliced

While the kohlrabi is cooking, melt butter in a small skillet over medium heat.

Add the leek and cook, stirring occasionally, until it is softened but not browned, about 5 minutes.

Remove from heat and set aside.

Step 3: Make the Cream Sauce

• 1 1/3 cups milk, divided
• 2 tablespoons all-purpose flour
• 3/4 teaspoon salt
• 1/4 teaspoon ground black pepper
• 1/8 teaspoon ground nutmeg

Heat 1 cup of milk in a small saucepan over medium heat until steaming but not boiling.

While the milk is heating, whisk together the flour and the remaining 1/3 cup milk in a small bowl to form a smooth paste.

Gradually stir the flour-milk paste into the steaming milk, whisking constantly, until the sauce thickens, about 2 to 3 minutes.

Remove from the heat and stir in the salt, pepper, and nutmeg.

I like to taste and adjust the seasoning at this stage for the perfect balance.

Step 4: Assemble the Gratin

• cooked kohlrabi from Step 1
• sautéed leek from Step 2
• cream sauce from Step 3
• 1 cup shredded Gruyère or Swiss cheese, divided
• 1/4 cup dry breadcrumbs

Arrange one-third of the cooked kohlrabi slices (from Step 1) evenly over the bottom of the prepared baking dish.

Top with half the sautéed leek (from Step 2) and drizzle over one-third of the cream sauce (from Step 3), then sprinkle with 1/3 cup cheese.

Repeat this layering with another third of the kohlrabi, the remaining leek, another third of the sauce, and another 1/3 cup cheese.

Finish with the remaining kohlrabi and sauce.

Sprinkle the top with the remaining 1/3 cup cheese and breadcrumbs.

Step 5: Bake and Serve

Bake the assembled gratin in the preheated oven until it is bubbling and golden brown on top, about 25 to 30 minutes.

Let it cool for 5 minutes before serving.

For an extra touch, I like to garnish with a little fresh parsley just before serving.