Creamy Spinach Mushroom Lasagna

Prep: 30 mins

Cook: 70 mins

Difficulty: Intermediate

Servings: 8 Servings

The best part of my childhood birthday celebration was getting to choose the menu for dinner on my big day. I always requested the same thing: pasta with a rich and creamy sauce. I remember digging into tortellini Alfredo with a paper party hat on and celebrating as an adult in front of a bowl of cacio e pepe. This year I celebrated with a slice of this creamy spinach mushroom lasagna.

This recipe was inspired by our extra-cheesy white lasagna, where a silky béchamel sauce is used in place of marinara (béchamel is also a core component in our traditional lasagna recipe). The original is made with crumbled sausage, but I prefer to substitute it with browned, sautéed mushrooms for a savory, satisfying, and more affordable filling. This creamy spinach mushroom lasagna is special occasion-worthy, though once you’ve tried it, you might not be patient enough to wait until the next time you’re celebrating.

Ingredients

12 dried lasagna noodles (not no-boil, about 2/3 of a 1-pound box)
1 pound baby spinach, or 1 (15- to 16-ounce) package frozen chopped spinach
1 (about 15-ounce) container whole-milk ricotta cheese (about 2 cups)
2 ounces finely grated Parmesan cheese (about 1/2 cup), divided
2 3/4 teaspoons kosher salt, divided
1/2 teaspoon freshly ground black pepper, divided
2 tablespoons olive oil
1 pound cremini or white button mushrooms, thinly sliced
1 medium yellow onion, finely chopped (about 1 1/2 cups)
3 cloves garlic, minced
1 teaspoon dried Italian seasoning
4 tablespoons (1/2 stick) unsalted butter
1/3 cup all-purpose flour
4 cups whole milk (1 quart)
1 pinch ground nutmeg
12 ounces low-moisture mozzarella cheese, shredded (about 3 cups), divided
Red pepper flakes, for serving (optional)
Torn fresh basil leaves, for serving (optional)

Instructions

Heat the oven to 400°F. Meanwhile, arrange 12 dried lasagna noodles in an even layer in a 9x13-inch baking dish. Cover the noodles with hot tap water and let soak while you prepare the rest of the ingredients, about 30 minutes.
If using frozen spinach, thaw 15 to 16 ounces according to package directions. Transfer to a clean kitchen towel, roll it up in the towel, and squeeze out all the excess moisture.
Stir 1 (about 15-ounce) container ricotta cheese, 1 ounce of the finely grated Parmesan cheese, 1/4 teaspoon of the kosher salt, and 1/4 teaspoon of the black pepper together in a medium bowl.
Heat 2 tablespoons olive oil in a large pot or Dutch oven over medium-high heat until shimmering. Add 1 pound thinly sliced cremini mushrooms mushrooms and cook, stirring occasionally, until the mushrooms have released their liquid, the liquid has evaporated, and the mushrooms have browned, 14 to 16 minutes.
Reduce the heat to medium. Add 1 finely chopped medium yellow onion, 1/2 teaspoon of the kosher salt, and the remaining 1/4 teaspoon black pepper. Cook, stirring occasionally, until the onion is translucent, about 4 minutes. Stir in 3 minced garlic cloves and 1 teaspoon dried Italian seasoning, and cook until the garlic is fragrant, about 1 minute.
If using fresh baby spinach, add 1 pound a few handfuls at a time and stir until just wilted, about 5 minutes. If using frozen spinach, add to pot and cook, stirring occasionally, until heated through, about 1 minute. Transfer to a plate.
Melt 1/2 stick unsalted butter in the same pot (no need to clean) over medium heat. Add 1/3 cup all-purpose flour and cook, whisking constantly, until bubbling and it begins to dry out slightly, about 2 minutes. Gradually whisk in 4 cups whole milk until smooth. Bring to a boil over high heat.
Reduce the heat to maintain a simmer and cook, stirring occasionally, until thickened, about 2 minutes. Stir in the remaining 2 teaspoons kosher salt and 1 pinch ground nutmeg. Remove the pot from the heat.
Drain the lasagna noodles and wipe the baking dish dry. If there is any accumulated liquid on the plate of spinach and mushrooms, pour it off.
Spread 1/4 cup béchamel sauce in the baking dish into a thin, even layer. Arrange 4 of the lasagna noodles in an even layer on top of the sauce, breaking them if needed to fit (it’s OK if the noodles overlap slightly). Dollop and spread 1/2 of the ricotta mixture (about 1 cup) over the noodles. Spoon 1/2 of the mushroom and spinach mixture (about 2 cups) over the ricotta. Sprinkle with 1 cup of the shredded mozzarella cheese. Dollop and spread about 1 heaping cup of the béchamel sauce over the mozzarella.
Repeat layering 4 more lasagna noodles, the remaining ricotta mixture, the remaining mushroom and spinach mixture, 1 cup of the mozzarella, and 1 heaping cup of the béchamel sauce. Top with the remaining 4 lasagna noodles, remaining béchamel sauce, remaining mozzarella, and remaining 1 ounce grated Parmesan.
Bake uncovered until the cheeses are melted and browned, and the sauce is bubbling, 30 to 35 minutes. Let cool for at least 10 minutes before serving. Garnish with red pepper flakes and torn fresh basil leaves if desired.