Pesto, potato and green beans lasagna

Directions

1. First of all, peal and clean the vegetables (peal the potatoes and clean the green beans... but maybe you already knew that!), then dice them (not too small, IMHO) and boil them, but keep them slightly underdone. Then pan-fry the vegetables with a drizzle of extra-virgin olive oil, a clove of garlic and, if you want, a spoon of pesto (so the vegetables can become tasty), and add salt consequently.
2. Now prepare the béchamel: warm up the milk in a pot, while in a thick-bottomed pot you melt the butter then, mixing with a whisk, add the flour, rosting them together for a minute. Then, pour the warm milk to the butter-flour compound and continue mixing with the whisk (so it won't lump), until the béchamel will be creamy.
3. Let the béchamel cool down, then add the pesto, so you'll have a green béchamel (if you want to use ready-made béchamel, simply add to it some pesto).
4. Now boil for a minute or two the lasagna sheets and let them dry on a clean dish cloth (to boil them I used a pan full of water, in which I poured a drizzle of oil, so the sheets wouldn't stick to each other): I boiled them two by two, so I could adjust the number of sheets to cook. Usually I don't boil the lasagna sheets but, in this case, since the béchamel is creamy (not fluid like ragù), the lasagna could be too dry, but if you boil the sheets (keeping them slightly underdone), you'll bypass the problem!
5. Now, you can arrange the lasagna! Take a capacious oven dish, put on the bottom of it a spoon of green béchamel, and then procede in this order: lasagna sheet, green béchamel (2 to 3 spoons, accurately spread), potatoes/green beans dice (as many as you want), grated parmesan cheese (as much as you want), and continue until ingredients exhaustion. My lasagna has 3 chubby layers!
6. One piece of advice: complete the lasagna with a béchamel-potatoes/green beans-parmesan cheese, so that you have a nice crisp crust!
7. Bake in a 390°F (200°C) oven for about 30 minutes!