In a large saucepan, heat 1 tablespoons of olive oil. Add the garlic and cook over moderate heat, stirring, until lightly browned, about 1 minute. Add the sausage and cook, breaking up the meat, until browned, about 8 minutes. Add the tomato puree, water, sugar, bay leaf, and fennel. Season with salt and pepper and bring to a boil. SImmer over low heat until thickened, about 30 minutes. Remove the garlic, mash it to a paste and stir it back into the pot, discard the bay leaf.
Meanwhile, Cook the penne in a larg pt of boiling water until al dente. Drain the pasta and return it to the pot. Stir the remaining 2 tablespoons of olive oil. Using a slotted spoon, add the cooked sausage to the pasta, then add 1 cup of the tomato sauce and toss to coat the pasta.
Spoon the pasta into a 9X13" baking dish. Pour the remaining tomato sauce over the pasta and dollup large spoonfuls of ricotta on top. Gently fold some of the ricotta into the pasta, don't overmix, you should have pockets of ricotta. Scatter the mozarella cubes on top and sprinkle with the Parmigiano-Reggiano. Bake the pasta for about 45 minutes or until bubbling and golden on top. Let rest for 20 minutes before serving.