This vegetarian lasagna still tastes so meaty with a luscious filling packed with mushrooms and other vegetables, along with lots of bechamel and cheese!
First, make the filling. Set up a food processor and put the mushrooms in its bowl. Pulse them until finely chopped to make room for the rest of the vegetables. Then add in the garlic, onion, carrot, celery, bell pepper and broccoli. Run the processor until it becomes pasty but still has some texture. Heat the olive oil in a large skillet with deep sides over medium high heat. Add the veggies and aromatics to the pan and let them cook through and become fragrant for about 6-8 minutes. While the mixture cooks, get a large pot of water on to boil for the lasagna. Then transfer the mixture to a large mixing bowl when it is done and set it aside to cool.
Use the same skillet to make the bechamel since it has a flavorful veggie base. Melt the butter in the skillet still over medium high heat. Whisk in the flour and keep whisking them together until you have a thick, golden paste. Keep whisking while you slowly pour in the milk until you have a lovely white sauce. Whisk in the salt and nutmeg, then let the sauce simmer and thicken for 10-15 minutes. Keep whisking it occasionally so that it doesn't become lumpy. While the bechamel cooks, finish the filling by stirring the ricotta, basil, parmesan, salt and pepper into the bowl with the veggies thoroughly. The water should be boiling by this point, so boil the noodles until tender for about 8 minutes. Drain them and set them aside to cool enough to handle.
Now you are ready to assemble. Pre-heat the oven to 350 and get out a 9 x 13 lasagna pan. Spread a thin layer of the bechamel sauce on the bottom of the pan, then lay out 4 lasagna noodles on top of the sauce. Spread another thin layer of bechamel on top of the noodles, followed by a thick, generous layer of the veggie filling and a big handful of mozzarella sprinkled on top. Repeat this layering twice more to have 3 layers total. You will probably only use about half of the filling. Freeze the rest for later use, it keeps for months! Then lay out the final 4 lasagna noodles on top, followed by the remaining bechamel in a thick layer and the rest of the mozzarella. Bake the lasagna for 45-50 minutes, until bubbly and slightly golden on top. Let it set for a few minutes and sprinkle more chopped basil on top. Then cut and serve! Makes great leftovers too.