There are a few things that make this a simple lasagna recipe. First are the no-boil lasagna noodles. They absorb liquid from the sauce to hydrate, eliminating the need to boil and cool them before using them. Then, since this is a vegetarian lasagna, there's no need to get out another pan to cook hamburger or sausages. And, finally, using frozen chopped spinach entails defrosting and squeezing it dry instead of cooking and chopping, then squeezing out the excess liquid.