Bring a large pot of water to a boil and salt the water. Add pasta and cook for a minute or two less time than the package directions. The pasta will soak up more juice and keep on cooking after you drain it, so it needs to be a little undercooked. The shells will probably cook for 9-10 minutes.
Pre-heat a big, deep skillet or medium size saucepan over medium heat.
Place garlic on a cutting board and place the flat of your knife on top of each clove. Carefully give the garlic a whack with the palm of your hand to separate the cloves from the skins. Throw out the skins and chop up the garlic.
Add EVOO by pouring a slow stream of it twice around the pan. This will be about 2 tablespoons, just enough to coat the bottom of the pan. Do not let the EVOO pour out too fast; you want a slow, steady stream. Add the garlic to the EVOO.
To chop the onion, cut the ends off and cut the whole onion down the center. Wrap half and save it for another use. Cut the other half into thin slices, then turn the slices a quarter turn and chop them again. Hold the tip of the knife on the cutting board and lift the back of the knife up and down over the onion to make the pieces really small. Add the chopped up onion to the garlic and oil. Cook, stirring a lot, until the onions are mushy and look cooked, about five minutes.
Add the tomatoes to the onions and stir. When the tomatoes come to a bubble, reduce the heat under the sauce to low. Stir in basil pieces to wilt them. Season the sauce with salt and pepper.
Preheat the broiler to high and place a rack in the center of the oven.
Drain pasta shells. Add them to a casserole dish. Add pesto sauce, ricotta cheese, and a handful of grated parmesan. Stir carefully and coat the hot pasta with the pesto and cheeses.
Pour the hot tomato sauce over the pasta, as much as you like. You can always have a little extra at the table.
Scatter the mozzarella cheese over the pasta. Add a final sprinkle of parmesan as well.
Place the casserole under the broiler in the middle of the oven, 10-12 inches from the heat. Let the cheese melt and bubble on top, 3-5 minutes.
This is one of many “Yum-o!” recipes – it’s good and good for you. To find out more about Yum-o!, Rachael’s nonprofit organization, go to www.yum-o.org.