Broccoli and Leek Lasagna

This yummy dish is a great way to switch up a classic lasagna recipe.
8-10 servings
Prep Time
Cook Time
Total Time


  • 1 stick (4 ounces) butter, divided
  • 3 leeks
  • 1 tablespoon olive oil
  • Salt
  • Black pepper
  • 3 heads broccoli
  • 12 ounces (3 cups) Le Gruyère AOP cheese, shredded and divided
  • 1/2 cup flour
  • 5 cups whole milk
  • 1/2 teaspoon ground nutmeg
  • 1 tablespoon Dijon mustard
  • 1 package oven-ready lasagna sheets


  1. Heat oven to 400F. Butter 9x13-inch pan; set aside.
  2. Prepare vegetables. Wash leeks and remove dark green portion. Thinly slice light green and white portions; set aside. Wash broccoli and chop into pieces (about 1/2 inch). Stems can be peeled and chopped, if desired. You should have about 6 cups chopped broccoli when finished.
  3. Heat large, heavy skillet or Dutch oven over medium heat. Add 1 tablespoon butter and olive oil. Add 2/3 sliced leeks, reserving the rest for topping the lasagna. Season with salt and pepper. Cook 5-7 minutes, stirring occasionally, until leeks are softened. Add broccoli to pan; season with salt and pepper. Cook, stirring occasionally, 5 minutes. Remove from heat. When mixture has cooled slightly, stir in 1/2 cup shredded Gruyère.
  4. Prepare sauce. Melt 6 tablespoons butter in sauce pan over medium heat. Whisk in 1/2 cup flour; cook 1 minute, stirring often. Slowly add milk, whisking constantly to incorporate. Sir in 2 teaspoons salt, 1/2 teaspoon black pepper, nutmeg and Dijon mustard. Increase heat to medium-high. Cook, stirring frequently, until sauce has thickened and coats the back of a spoon. Reduce heat to low. Add 2 cups shredded Gruyère, one handful at a time, stirring until melted.
  5. Assemble lasagna. Ladle about 1 cup sauce over bottom of pan. Top with three lasagna sheets. (There will be some space between the lasagna sheets, but they will expand while cooking). Top with 1/4 broccoli leek mixture, spooning evenly over lasagna sheets. Top with another 1 cup sauce. Repeat 3 times. Top with another layer of lasagna sheets and remaining sauce. Finish with reserved chopped leeks and remaining 1/2 cup shredded Gruyère.
  6. Cover dish with foil and place on foil-lined baking sheet. Bake, covered, 40 minutes. Carefully remove foil and bake additional 20-31 minutes, until lasagna is bubbling and top is golden brown. Allow to cool for 10 minutes before serving.