Pre-heat oven to 180℃/350F
Bring a large pot of water to the boil. Add pasta and cook per packet directions minus 1 minute. Drain and rinse under water and set aside.
In a bowl toss the chicken thigh pieces together with the garlic powder and oregano.
Heat a large saucepan/skillet over medium high heat. Add the olive oil and cook the chicken for around 3 minutes, until lightly golden on the outside (will still be raw in the middle). Remove to a plate and set aside.
In the same pan add the onion and cook for about 2 minutes. Add the garlic and bell pepper and saute gently until onion is soft and translucent (around 3 mins.) Stir in the the tomato paste and dried oregano and stir for a further minute.
Add the passata and chicken stock (I usually pour the chicken stock into the empty passata bottle, give it a quick shake to catch any remaining sauce, and add that to the pan). Bring to a gentle simmer, return the chicken and allow to simmer for around 5 mins. Stir in the cream, spinach and peas, cooking until the spinach has wilted. Taste and season accordingly.
Stir in the cooked pasta and gently stir to combine, then transfer the mixture to a large baking dish.
Top with the grated mozzarella and parmesan. Place in the oven for 20-25 minutes. The dish should be hot throughout and the cheese golden and bubbly.