Preheat your oven to 375°F (190°C) to ensure even cooking and a golden top.
In a large pot, bring salted water to a boil. Add the pasta and cook according to package instructions until al dente. Drain and set aside.
Heat olive oil in a large skillet over medium heat. Add chopped onion and sauté until translucent, about 3-4 minutes. Stir in minced garlic and cook for another minute until fragrant.
Add diced chicken to the skillet. Season with oregano, basil, parsley flakes, vegetable stock powder, and a pinch of salt. Cook, stirring occasionally, until no longer pink, about 7-8 minutes.
Stir in halved cherry tomatoes, Passata (or tomato sauce), and tomato paste. Simmer for about 5 minutes. In a separate bowl, whisk milk and cornflour/cornstarch mixture until smooth. Pour into skillet, stir, and cook another 2-3 minutes until sauce thickens.
Add cooked pasta to the skillet and toss to coat with sauce.
Transfer pasta mixture to an oven-safe baking dish. Sprinkle grated mozzarella and parmesan cheese on top.
Bake in preheated oven for 20-25 minutes until cheese is melted, bubbly, and golden.
Remove from oven and let sit a few minutes before serving. Enjoy with a light salad or crusty bread.