In a large skillet or wide pot, over medium heat sauté onions and garlic in olive oil for 3 minutes. Then sprinkle in red pepper flakes and cook for 1 more minute.
Mix in crushed tomatoes and tomato paste and simmer for 5 minutes.
Carefully transfer to a blender, add sugar and and basil and mix until well combined.
Return your sauce to the pan, slowly mix in cream and butter. Cook over medium heat for 3-4 minutes , then your ready to serve on your favorite pasta!
This is good for 7 days in the refrigerator.