Mix bechamel sauce with pesto, preheat oven to 180 degrees Celsius and now the assembly. Add a dollop of sauce on the base of the baking dish, line with sheet of lasagna, add another dollop of sauce, spread evenly, sprinkle parmigiana evenly, top in a single layer of beans, top with potato slices and another sheet of lasagna, repeat the procedure with a final lasagna sheet on top, spread out remaining sauce and sprinkle parmigiana, bake for 20 minutes covered and 10 minutes uncovered. enjoy!