Ultra-Creamy Spinach and Mushroom Lasagna Recipe

[Photographs: J. Kenji Lopez-Alt] Note: Mushrooms can be chopped with a knife. Alternatively, break them with your fingertips, or pulse them in a food processor. They should be chopped until no pieces larger than 1/4-inch remain. Yield:serves 6 to 8 Active time:1 hour Total time:1 1/2 hours Rated:4 Ingredients 8 tablespoons (1 stick) unsalted butter, […]