• Preheat oven to 400 degrees Fahrenheit.

Béchamel Sauce

• Prepare a bechamel sauce by melting ¼ cup unsalted butter in a large saucepan over medium heat.
• Once the butter is melted, add in ¼ cup of all-purpose flour and stir to combine the flour and butter to make a roux.
• Next, slowly add in 4 cups of whole milk. Stir continuously to allow the sauce to thicken. Once the sauce coats the back of a wooden spoon, your bechamel sauce is ready. Remove from heat and stir in the kosher salt, black pepper, and ground nutmeg.
• Set the white sauce to the side, covered, and continue working on preparing the remaining parts of the lasagna.

Lasagna Filling

• Heat 3 tablespoons olive oil in a large skillet over medium heat.
• Add 1 cup of sliced or diced onions and cook until they just begin to caramelize. Add in the garlic. Stir for one minute until just fragrant.
• Add the ground beef. Cook ground beef until it browns, about 5 to 7 minutes.
• Add in the spinach and cook until spinach is wilted, about 5 minutes.
• Season with a few pinches of kosher salt and ground black pepper. Taste and adjust seasoning as desired.

Lasagna Assembly

• To begin the layering process for the lasagna, spoon a ladle full of tomato sauce on the bottom of the baking dish.
• Next, add enough no-boil lasagna noodles to cover the bottom of the baking dish. Add a ladle of béchamel to cover the noodles.
• Add the meat and veggie filling followed by a ladle of tomato sauce. Top with more no-boil noodles. Repeat the layering process until the top layer reaches the top of the pan.
• Pour the remaining sauce and bechamel on top. Sprinkle a bit of fresh mozzarella cheese and grated parmesan cheese over the top.
• Bake the lasagna for 30 to 40 minutes until edges are golden brown and the cheese is bubbly. Remove from the oven and allow to cool slightly before garnishing with chopped fresh basil.