Sauté the onion, garlic, and chilli flakes in olive oil.
olive oil, onion, garlic, chilli flakes
Add the canned tomatoes, sugar, and mascarpone, and simmer until thickened.
canned chopped tomatoes, mascarpone, caster sugar
In a separate pan, cook the chicken until it is cooked through.
skinless chicken breasts
Cook the penne pasta according to package instructions, then toss with olive oil.
penne pasta
Combine the pasta, chicken, and sauce in an ovenproof dish, and top with grated cheddar, mozzarella, and parsley.
grated mozzarella cheese, parsley, mature cheddar cheese
Bake until golden brown and bubbling.