Chop the chicken breasts into bite-size pieces.

Fry the chicken in a frying pan with the onions and meatballs until cooked through.

In a large pan, add the chopped tomatoes and chili flakes.

Bring the tomato mixture to a boil.

Add the sweet chili sauce and stir to combine.

Add the chicken, meatballs, and onions to the sauce.

Simmer the sauce on low heat.

Cook the penne pasta according to package directions.

Drain the pasta and add it to the sauce.

Combine the pasta and sauce thoroughly and serve.