Place the beef stew meat, carrots, potatoes, onion, and garlic into the slow cooker.
Stir in the Guinness, beef broth, tomato paste, thyme, salt, and pepper until the tomato paste dissolves.
Cover and cook on low for 7 hours until the beef is tender.
In a bowl, mix the flour, baking powder, cheddar cheese, and parsley.
Add the milk and melted butter to the dry mix and stir just until a thick dough forms.
Drop spoonfuls of the dough onto the surface of the stew.
Cover and cook on high for 1 more hour until the dumplings are firm and cooked through.