Boil water, add the pasta and simmer gently for 4 minutes.
Cook the onions and garlic in the olive oil until soft. Add the tomatoes, basil, coconut milk and coconut aminos if using.
Bring to a boil and then simmer gently until the sauce thickens slightly.
Taste, add salt and pepper.
Add the sauce, and arugula to the Penne, heat through until the arugula starts to wilt, then serve immediately.