1. Preheat your oven to 375°F (190°C). If using regular lasagna noodles, bring a large pot of salted water to a boil and cook the noodles according to package instructions until al dente. Drain and set aside on a lightly oiled sheet to prevent sticking.
2. In a large skillet, heat olive oil over medium heat. Add chopped onion and sauté for about 5 minutes until soft and translucent. Add minced garlic and cook for another minute until fragrant.
3. Add sliced mushrooms to the skillet. Cook, stirring occasionally, until the mushrooms release their moisture and start to brown, about 8-10 minutes. Season with 1/2 teaspoon salt and pepper. Remove from heat and stir in the chopped spinach, allowing the residual heat to wilt it slightly.
4. To make the béchamel sauce, melt butter in a medium saucepan over medium heat. Once melted, whisk in the flour and cook for about 2 minutes until it forms a smooth paste and starts to bubble but doesn’t brown.
5. Slowly whisk in the warmed milk, a little at a time, making sure no lumps form. Continue whisking constantly until the sauce thickens, about 5-7 minutes. Add remaining 1/2 teaspoon salt, pepper, and nutmeg for warmth and depth. Remove from heat.
6. In a mixing bowl, combine ricotta cheese with a few spoonfuls of the béchamel to loosen it up, then fold the mushroom and spinach mixture into the ricotta for added flavor and texture.
7. Spread a thin layer of béchamel sauce on the bottom of a 9×13 inch baking dish. Layer three lasagna noodles over the sauce.
8. Spread one-third of the ricotta and vegetable mixture evenly over the noodles, then drizzle with a third of the béchamel, and sprinkle with a third of the shredded mozzarella. Repeat this layering process two more times, finishing with a generous sprinkle of Parmesan cheese on top.
9. Cover the dish tightly with foil and bake for 30 minutes. Remove the foil and bake for an additional 10-15 minutes, until the top is golden and bubbly.
10. Let the lasagna rest for 10 minutes before slicing. This step is crucial—it helps the layers set and makes serving easier. Garnish with fresh basil or parsley if desired.

I’ve found that letting the lasagna cool a bit before cutting is a trick that even novice cooks appreciate. It’s one of those small moments in the kitchen that can turn a good meal into a great one.