Moist Leek Tart with Gruyere and Onions

There’s something so comforting about a homemade tart, especially one filled with leeks and gruyere cheese. I’ve always loved how the kitchen smells when onions are slowly cooking on the stovetop, getting all sweet and soft. It reminds me of those cozy Sunday afternoons when I have time to take things slow in the kitchen.

This leek tart is one of those recipes I turn to when I want something that feels a bit fancy but doesn’t require hours of work. The combination of buttery pastry, melted gruyere, and tender leeks just works so well together. I often make it for lunch when friends come over, or as an easy dinner with a simple salad on the side.

If you’re like me and enjoy savory baked goods that don’t need constant attention while cooking, this recipe is right up your alley. You can even prep most of the components ahead of time, which makes the actual assembly a breeze.

What Kind of Leeks Should I Use?

For this tart, you’ll want to look for fresh leeks with long, straight white stems and crisp, dark green leaves. The most common variety you’ll find at the grocery store is the American Flag leek, which is perfect for this recipe. When shopping, pick leeks that are about 1-2 inches in diameter – anything much larger can be tough and woody. Only the white and light green parts will be used in the tart, but don’t toss those dark green tops – they’re great for making stock. Remember to clean your leeks thoroughly, as dirt often hides between the layers – slice them lengthwise and rinse under running water to remove any grit.

Options for Substitutions

This tart recipe has some room for flexibility with ingredients. Here’s what you can swap:

• Gruyere cheese: If Gruyere is hard to find or too pricey, Swiss cheese, Emmental, or aged white cheddar make great alternatives. They all offer that nice melty texture and nutty flavor that works well in this tart.
• Leeks: No leeks? You can double up on the yellow onions, or use a mix of shallots and onions instead. Just cook them the same way as you would the leeks.
• Thick cream: Heavy cream or half-and-half will work here. If using half-and-half, add an extra egg yolk to maintain the creamy texture.
• All-purpose flour: For the crust, you need to stick with all-purpose flour to get the right texture. Pastry flour can work too, but avoid whole wheat flour as it will make the crust too heavy.
• Cumin: Since it’s optional, you can skip it or try other herbs like thyme or herbes de Provence for a different flavor profile.

Watch Out for These Mistakes While Baking

The success of your leek tart largely depends on how you handle the pastry – working with warm butter or overworking the dough will result in a tough, chewy crust instead of the flaky texture we’re after. Another common mistake is not cleaning the leeks thoroughly enough – these vegetables can hide dirt between their layers, so it’s essential to slice them first, then rinse well in a colander before cooking. The filling can become watery if you don’t cook the leeks and onions long enough – make sure to sauté them until they’re soft and most of their moisture has evaporated, about 15-20 minutes over medium heat. For the best results, blind bake your crust for 15 minutes before adding the filling, and let the tart rest for 10-15 minutes after baking – this helps the filling set properly and makes it easier to slice cleanly.

What to Serve With Leek Tart?

This savory tart pairs perfectly with a simple green salad dressed in a light vinaigrette – the crisp, fresh greens balance out the rich, creamy filling. If you’re serving this for lunch, add a bowl of light soup on the side, like a classic French carrot soup or clear vegetable broth. For dinner, try serving it with roasted vegetables like asparagus or Brussels sprouts, which complement the leeks and onions without overpowering the delicate flavors of the tart. A glass of crisp white wine, like Sauvignon Blanc or Chablis, makes this meal feel extra special!

Storage Instructions

Keep Fresh: This leek tart stays good in the fridge for up to 3 days when wrapped well or stored in an airtight container. The pastry might soften a bit, but the flavor actually gets even better as the ingredients have time to meld together!

Make Ahead: You can prep parts of this tart in advance to save time. Make the pastry dough up to 2 days ahead and keep it wrapped in the fridge. The leek and onion filling can also be cooked a day before and stored in the fridge until you’re ready to assemble.

Warm Up: To enjoy leftover tart, let it come to room temperature for about 15 minutes, then warm it in a 350°F (175°C) oven for about 10 minutes. This helps bring back some of that lovely crispy crust. I prefer this method over microwaving, which can make the pastry soggy.

Preparation Time	60-90 minutes
Cooking Time	35-50 minutes
Total Time	95-140 minutes
Level of Difficulty	Medium

Estimated Nutrition

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

• Calories: 900-1000
• Protein: 25-30 g
• Fat: 60-70 g
• Carbohydrates: 80-90 g

Ingredients

• 180 grams all-purpose flour
• A pinch of salt
• 90 grams very cold unsalted butter
• 60 ml chilled water
• 2 leeks
• 1 small yellow onion
• 30 grams unsalted butter (or use olive oil)
• 1/2 teaspoon garlic, minced
• 2 large eggs
• 120 ml thick cream
• 1 teaspoon regular salt
• 1/2 teaspoon black pepper
• 1 teaspoon ground cumin (optional)
• 35 grams gruyere cheese, shredded

Step 1: Prepare the Shortcrust Pastry

In the bowl of your food processor, place the flour and salt.

Add the cold butter, cut into small cubes, and blend until the mixture resembles small crumbs.

Slowly incorporate the cold water, adding a little at a time and blending between each addition.

Stop adding water as soon as the dough comes together.

Step 2: Roll and Chill the Dough

Transfer the dough onto a lightly floured sheet of baking paper, forming it into a disk.

Place a second sheet of baking paper over the dough and roll it into a large rectangle using a rolling pin.

Chill the rolled dough in the fridge for at least 1 hour to let it rest.

Step 3: Line and Prepare the Baking Pan

Remove the dough from the fridge and peel off the baking paper.

Line your baking pan with the shortcrust pastry.

For this recipe, a 14 x 4.5 inch (35 x 10 cm) rectangular pan or a round 9.5 inch (24 cm) tart pan can be used.

Poke small holes all over the pastry with a fork.

Place the lined pan back in the fridge for 30 minutes to 1 hour, and put it in the freezer for the last 15 minutes before baking.

Step 4: Blind Bake the Pastry

Preheat your oven to 180°C (350°F).

Blind bake the pastry for 10 to 15 minutes, then set aside to cool while you prepare the filling.

Step 5: Cook the Leek and Onion Filling

Wash the leeks and chop them into thin slices.

Thinly slice the brown onion.

Melt the butter in a non-stick pan over medium heat, and sauté the chopped leeks, sliced onion, and minced garlic for about 5 minutes until the onions are translucent.

Remove from heat and let cool slightly.

Step 6: Prepare and Bake the Tart

In a separate bowl, whisk together the eggs, heavy cream, salt, pepper, and cumin.

Add the sautéed leeks and onions to the egg mixture, and stir in the grated Gruyere cheese.

Pour this mixture over the pre-baked pastry and bake for another 25 to 35 minutes, until the leeks are lightly golden and the filling is set.

Serve the tart warm.