In your slow cooker add wine, broth, tomato paste, thyme, garlic, salt and pepper. Stir to combine. Sprinkle onions as evenly as possible on the bottom of the slow cooker. Add beef and cover. Cook on low for 6-8 hours, or until beef is tender. In a cup or small bowl stir together cream and flour until smooth. Remove beef from slow cooker and you have 2 options at this point. You can either pour juices from your slow cooker into a saucepan and on medium high heat bring to a gentle boil. Add in cream mixture and stir until thickened. The other option is to turn your slow cooker up to high and add cream mixture to your slow cooker. Stir until fully combined and leave covered for about 15 minutes, or until thickened. Regardless, this gravy is delicious. Serve with beef. Enjoy!