Bring a large pot of water to the boil. Add the pasta and cook according to packet instructions, then drain (reserving a cup of the water) and leave to one side.
Peel and finely chop the onion. Put a pan on a medium heat and add the oil. Add the onion and salami and cook for 2-3 minutes.
Add the tomatoes and the reserved cup of pasta water. Simmer for 5 minutes, then add the red pepper paste and cream cheese. Stir well.
Tip the pasta in and toss in the sauce. Taste and season with salt and pepper as needed.