Bring a large pot of salted water to a boil. Cook the pasta in the salted boiling water until very al dente, about 2 minutes less than the package directions. Drain and add the pasta back to the pot. Set aside.
Preheat the oven to 425°F and set the rack in the middle position. Butter a 9 x 13-inch oven-safe baking dish; set aside.
Heat the olive oil in a large nonstick skillet over medium-high heat. Crumble the sausage into the pan and cook, breaking apart with a wooden spoon, until browned, 8 to 10 minutes.
Add the onion, pepper, and garlic and sauté until they start to soften, about 5 minutes.
Add the crushed tomatoes, sugar, red pepper flakes, and black pepper. Stir and bring to a simmer, uncovered, for 15 minutes. Add the heavy cream, ¼ cup of the Parmesan, and cilantro to the pan; stir until evenly combined.
Taste and adjust salt as necessary. Carefully pour the mixture from the skillet into the large pot with the pasta and gently stir to combine. Spoon half of the mixture into the prepared baking dish.
Sprinkle with half of the shredded mozzarella and half of the remaining Parmesan. Spoon the remaining pasta mixture on top and sprinkle with the rest of the mozzarella and Parmesan.
Transfer the dish to the oven and bake, uncovered, until it is completely heated through and the cheese has melted and is lightly browned, about 20 to 25 minutes. Let it rest for 5 minutes before cutting.