Begin by gathering all necessary ingredients. Preheat your oven to 400°F (200°C) and lightly grease a baking dish.
In a large pot, bring lightly salted water to a boil. Add the penne and cook, stirring occasionally, until it reaches an al dente texture, approximately 11 minutes. Drain the pasta, reserving 1 cup of the cooking water.
In a large skillet over medium heat, heat the olive oil. Sauté the chopped onion until it becomes soft and translucent, which should take around 5 minutes. Add the minced garlic and cook for an additional 30 seconds until fragrant.
Incorporate the tomato sauce and tomato paste into the skillet, allowing the mixture to cook down slightly for about 5 minutes.
Next, pour in the heavy whipping cream and add the grated Parmesan cheese. Season this mixture with a pinch of sugar, salt, and black pepper.
Mix in some of the reserved pasta water to achieve your desired sauce consistency, then add the cooked penne to the skillet.
Remove the skillet from heat and gently fold in the halved cherry tomatoes, half of the shredded mozzarella cheese, and the chopped basil. If necessary, add more pasta water to maintain the desired texture.
Transfer the pasta mixture into the prepared baking dish, ensuring it is evenly distributed. Top with the remaining mozzarella cheese.
Bake in the preheated oven until the cheese is melted and bubbly, approximately 20 minutes. Serve hot and enjoy!