Cook the chopped bacon in a skillet over medium heat until crisp. Remove the bacon with a slotted spoon and set it aside, leaving the drippings in the pan.
Toss the beef chunks with flour, salt, and pepper. Brown the beef in the bacon drippings for 3-4 minutes per side, then transfer it to the slow cooker.
Add the pearl onions, carrots, potatoes, and garlic to the slow cooker. Stir in the tomato paste, smoked paprika, and thyme.
Pour the Guinness and beef broth over the ingredients. Add the cooked bacon and stir gently to combine.
Cover and cook on low for 7-8 hours until the beef is fork-tender. Taste and adjust salt if needed before serving.
Sprinkle with fresh parsley right before serving.