Add half of the basil, garlic, all of the cheese and the peanuts, and then go with half of the olive oil. You can do this with a food processor or just a hand blender.
Add the rest of the basil and blitz again, adding the rest of the olive oil as you go.
Melt the butter, then add the flour and cook for 1-2 minutes.
Add the milk little by little while mixing.
Season with nutmeg, salt and pepper.
Use a hand blender to make the béchamel nice and smooth.
Cook the pasta for 1 minute, then place on a kitchen cloth.
Butter the baking tin, then layer the lasagna with pasta, béchamel, pesto, and Parmesan, repeating the layers.
Top with extra Parmesan.
Bake in the oven for 30-40 minutes until golden brown.
