01 - Preheat oven to 425°F (220°C).
02 - Cook pasta in a large pot of salted boiling water for 2 minutes less than package instructions. Drain and set aside.
03 - While pasta cooks, heat olive oil in an oven-safe skillet over medium heat. Add chopped onion and sauté for 2-3 minutes until translucent.
04 - Add minced garlic and cook for 30 seconds until fragrant.
05 - Stir in cherry tomatoes, oregano, and chili flakes if using. Cook for 4-5 minutes, stirring occasionally, until tomatoes begin to soften and release juices.
06 - Pour in heavy cream, season with salt and pepper, and stir to combine.
07 - Add drained pasta to the skillet and toss to coat evenly in the sauce.
08 - Scatter mozzarella and half the Parmesan over the pasta. Stir gently, then top with the remaining Parmesan.
09 - Transfer skillet to the preheated oven and bake for 10-12 minutes, until the cheese is bubbling and golden.
10 - Remove from the oven, garnish with fresh basil, and serve immediately.