Heat the olive oil in a large sauté pan over medium high heat. After a minute or two, add in the onions and cook until translucent and tender, about 3 to 4 minutes. Add the garlic and stir together for one minute. Add in the lean ground beef and cook until all the meat is browned and cooked through.
Add in the anchovy paste and the red chili pepper flakes if using and stir together. Pour in the crushed and diced tomatoes, mix together and bring to a simmer. Let simmer for about 8 to 10 minutes.
Pour in the heavy cream* and add in the basil. Stir together for a minute to two and then add in the cooked rigatoni pasta. Stir together and make sure the sauce is coating all of the pasta. Taste, season with salt and pepper if needed and serve. Serve with freshly grated parmesan cheese and enjoy!
Notes
*If you don't have heavy cream, whole milk will work, or for an even creamier pasta, 3/4 whole milk + 3 tablespoons unsalted butter.