- 1 butternut squash, peeled and thinly sliced
- ground nutmeg
- 2 tablespoons butter
- 1 leek, thinly sliced
- 2 1/2 cups baby spinach leaves
- 1/2 cup whole milk
- 1/3 cup grated Parmesan cheese
- 2 tablespoons rice flour
- 1 tablespoon balsamic vinegar
- 1 teaspoon Worcestershire sauce
- 1 teaspoon onion powder
- ground black pepper to taste
- 2 cups ricotta cheese
- Bechamel Sauce:
- 3 tablespoons butter
- 2 tablespoons all-purpose flour
- 2 cups milk
- 1 teaspoon salt
- 1/8 teaspoon freshly grated nutmeg
- Preheat oven to 425 degrees F (220 degrees C). Line 2 baking sheets with parchment paper.
- Arrange butternut squash slices on the baking sheets. Sprinkle 1 pinch nutmeg on top.
- Bake in the preheated oven until pliable but not mushy, about 5 minutes per side.
- Melt 2 tablespoons butter in a large saucepan over medium heat. Add leek and spinach; cook and stir until wilted, about 5 minutes.
- Stir 1/2 cup milk, Parmesan cheese, rice flour, balsamic vinegar, Worcestershire sauce, onion powder, and black pepper into the saucepan until combined and slightly thickened, about 5 minutes.
- Arrange half of the butternut squash in the bottom of an 8-1/2×11-inch casserole dish. Layer leek mixture and ricotta cheese on top. Arrange remaining butternut squash on top.
- Bake lasagna in the preheated oven until golden, about 40 minutes.
- Melt 3 tablespoons butter in a large saucepan over medium heat. Stir in flour until a golden paste forms, 5 to 10 minutes. Increase heat to medium-high; slowly whisk in 2 cups milk until thickened and bubbling. Reduce heat to medium-low and simmer sauce until smooth, 10 to 20 minutes.
- Season sauce with salt and 1/8 teaspoon nutmeg. Pour over lasagna.