Bring a large pot of water to a boil. Add the lasagna noodles and cook until slightly firmer than al dente, about 2 minutes less than the package instructions. Drain the noodles and arrange them in a single layer on a tray or clean kitchen towel so that they do not stick together.
12 pieces lasagna noodles
Heat the olive oil in a large skillet over medium-high heat. Add the mushrooms and cook for 5 to 7 minutes, until they release their liquid and most of it evaporates.
2 tablespoons olive oil, 8 oz white mushrooms
Add the onion and carrots, then saute for 4 minutes. Add the broccoli and cook for another 3 minutes. Stir in the garlic, Italian seasoning, salt, and ground black pepper, and cook for 1 minute. Remove the skillet from the heat and set the vegetables aside.
1 piece yellow onion, 1 cup carrots, 2 cups broccoli florets, 3 cloves garlic, 1 teaspoon Italian seasoning, 1/2 teaspoon salt, 1/4 teaspoon ground black pepper
Melt the butter in a saucepan over medium heat. Add the flour and whisk until smooth, then cook for 1 minute while whisking. Do not let the mixture turn brown.
4 tablespoons butter, 1/2 cup all-purpose flour
Gradually pour in the milk while whisking continuously, and let the sauce reach a gentle simmer. Cook for 5 to 7 minutes, stirring regularly, until it is smooth and thick enough to coat the back of a spoon. Add the salt, ground black pepper, and nutmeg. Stir, then remove the saucepan from the heat.
4 cups whole milk, 3/4 teaspoon salt, 1/4 teaspoon ground black pepper, 1/8 teaspoon ground nutmeg
Combine the ricotta cheese, egg, 1/2 cup Parmesan cheese, and ground black pepper in a bowl. Mix until well blended.
15 oz whole-milk ricotta cheese, 1 piece egg, 1/2 cup grated Parmesan cheese, 1/4 teaspoon ground black pepper
Preheat the oven to 375°F. Spread 1/2 cup of the white sauce over the bottom of a 9 x 13-inch baking dish, then arrange 3 lasagna noodles over the sauce.
12 pieces lasagna noodles
Spread one-third of the ricotta mixture over the noodles. Add one-third of the cooked vegetables, followed by 3/4 cup of white sauce and 1/2 cup mozzarella cheese. Repeat these layers two more times, using 3 noodles, ricotta mixture, vegetables, white sauce, and mozzarella for each layer.
15 oz whole-milk ricotta cheese, 2 1/2 cups shredded mozzarella cheese
Arrange the remaining 3 lasagna noodles on top. Pour all of the remaining white sauce over the noodles, making sure that they are completely covered. Top with the remaining 1 cup mozzarella cheese and 1/2 cup Parmesan cheese.
12 pieces lasagna noodles, 2 1/2 cups shredded mozzarella cheese, 1/2 cup grated Parmesan cheese
Cover the baking dish loosely with aluminum foil, keeping the foil from touching the cheese. Bake for 30 minutes. Remove the foil and continue baking for 15 to 20 minutes, or until the sauce is bubbling around the edges and the cheese is lightly browned.
Remove the lasagna from the oven and let it rest for 15 minutes before slicing. Serve warm. Share and enjoy!