Ingredients:
- 450g (1 lb) cremini or white button mushrooms, thinly sliced
- 280g (10 oz) fresh baby spinach, roughly chopped
- 15g (3 cloves) garlic, minced
- 30ml (2 tbsp) olive oil
- 3g (½ tsp) salt
- 1g (¼ tsp) black pepper
- 56g (4 tbsp) unsalted butter
- 30g (¼ cup) all-purpose flour
- 710ml (3 cups) whole milk, warmed
- 1g (¼ tsp) ground nutmeg
- 3g (½ tsp) salt
- 425g (15 oz) whole milk ricotta cheese
- 1 large egg, lightly beaten
- 50g (½ cup) grated Parmesan cheese
- 30ml (2 tbsp) fresh parsley, chopped
- 300g (9 to 12) no-boil lasagna noodles
- 340g (3 cups) shredded mozzarella cheese
Instructions:
- Heat olive oil in a large skillet over medium-high heat. Add mushrooms and cook without stirring for 3 minutes to achieve a mahogany-colored sear. Stir in minced garlic and spinach, cooking only until the spinach has wilted and all excess liquid has evaporated from the pan. Set aside.
- Melt butter in a saucepan over medium heat. Whisk in flour and cook for 1-2 minutes until the mixture smells nutty but hasn't browned. Gradually pour in warmed milk, whisking constantly to eliminate lumps. Simmer until the sauce is thick and glossy enough to coat the back of a spoon. Stir in nutmeg and salt.
- In a medium bowl, combine ricotta, beaten egg, Parmesan, and parsley. Stir until smooth.
- Spread a thin layer of white sauce on the bottom of the baking dish. Place a layer of noodles on top. Spread one-third of the ricotta mixture, followed by a third of the mushroom-spinach filling, and a drizzle of white sauce. Repeat these layers until all ingredients are used, ending with a final layer of noodles topped with the remaining white sauce and a heavy blanket of mozzarella.
- Cover the dish with foil (tented so it doesn't stick to the cheese). Bake at 375°F (190°C) for 20 minutes. Remove the foil and bake for another 10-15 minutes until the cheese is bubbly and features golden-brown charred spots.