01 - Bring a large pot of salted water to a boil. Cook the penne according to package directions until al dente. Reserve 1/2 cup of pasta cooking water, then drain the pasta.
02 - While pasta cooks, heat olive oil in a large skillet over medium heat. Add minced garlic and chopped onion; sauté for 2–3 minutes until softened and fragrant.
03 - Stir in crushed tomatoes, sugar, red pepper flakes, salt, and black pepper. Let the sauce simmer for 10–12 minutes, stirring occasionally to develop flavors.
04 - Add the drained penne to the skillet with the tomato sauce. Toss thoroughly to coat the pasta, adding a splash of the reserved pasta water if needed to achieve a silky consistency.
05 - Gently fold in ricotta cheese, half of the torn basil leaves, and grated Parmesan. Cook for 1–2 minutes until everything is heated through and the ricotta is warmed.
06 - Divide the pasta among serving plates. Top each portion with the remaining fresh basil and additional grated Parmesan cheese.