How to Make It
Preheat the oven to 400°. In a large saucepan, heat 1 tablespoon of the 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 sauce; discard the bay leaf.
Meanwhile, cook the penne in a large pot of boiling salted water until al dente. Drain the pasta and return it to the pot. Stir in 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 penne.
Spoon the pasta into a 9-by-13-inch baking dish. Pour the remaining tomato sauce over the pasta and dollop large spoonfuls of the Creamy Ricotta on top. Gently fold some of the ricotta into the pasta; don't overmix—you should have pockets of ricotta. Scatter the mozzarella 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.