This Leek and Gruyere Grilled Cheese recipe is rich and buttery. Every bite is infused with perfectly melted cheese and that subtle, savory, onion flavor leeks are known for. The perfect easy weeknight dinner with a simple salad or light soup!
8slicessourdough bread multigrain, white, whole wheat, or other kinds of bread can also be used
Melt 1 tablespoon of the butter in a cast iron (or other heavy) skillet over medium heat. Sauté the leeks in the butter with a pinch of salt for about 1 minute, until starting to soften. Add 1/4 cup of water, stir, and allow to continue to cook for about 5 minutes, or until leeks are very soft and water has evaporated, with almost a melted texture, adding more water if necessary and stirring occasionally as they cook.
Meanwhile, use the remaining 3 tablespoons of butter to spread on one side of each piece of bread. Place four of the slices butter-side-down on a cutting board or plate.
In a small bowl, mix together the mayonnaise (1/4 cup) and the grated gruyere cheese (1.5 cups), along with the cooked leeks. Season to taste with salt and pepper.
Divide the leek and cheese mixture evenly on top of the butter-side-down pieces of bread. Place remaining four pieces of bread butter-side-up on top of each sandwich.
In the same skillet (you can use a grill pan or panini press if you prefer), grill the sandwiches on medium heat for about 3 minutes on each side in two batches. If sandwiches are cooking too quickly, turn heat down. I recommend covering the skillet while you cook the first side so the cheese melts more rapidly- this will make flipping the sandwiches easier since the sandwich will be "glued" together by the cheese.
Cut in half and serve immediately while hot and melty!
Washing the leeks: Leeks are notoriously dirty, so it's important to clean them thoroughly. After trimming off and discarding the root and dark green parts, slice lengthwise and then into slices about 1/4" thick. Place in a bowl of water, stir around to separate the layers, and allow to sit for 30 seconds or so. The dirt will sink, the leeks will float. Use a slotted spoon to remove the leeks and place in a colander. Give them one final rinse in the colander. Don't dump the water from the bowl on top with the leeks into the colander, as this will just add the dirt back on top of them.
Traditional gruyere cheese may not be suitable for a strict vegetarian diet because it contains animal rennet. Look for a suitable vegetarian substitute, such as a gruyere made with plant rennet, or use another kind of cheese as a substitution, such as mozzarella or cheddar.
The provided nutrition information does not include any added sodium from seasoning to taste, any optional ingredients, and it does not take brands into account. Feel free to calculate it yourself using this calculator or by adding the recipe to Yummly.