Season the beef cubes with salt and black pepper.
In a large skillet, heat the olive oil over medium-high heat. Sear the beef cubes in batches until browned on all sides, about 5 minutes. Transfer the beef to the slow cooker.
In the same skillet, lower the heat and add the minced garlic, cooking until fragrant (about 30 seconds). Add the butter and let it melt, stirring to combine.
Pour the garlic butter mixture over the beef in the slow cooker. Add the beef broth, Worcestershire sauce, and dried thyme. Stir to coat.
Add the halved baby potatoes to the slow cooker, gently mixing them with the beef and sauce.
Cover the slow cooker and set it to low heat for 6 hours or high heat for 3 hours, until the beef is tender and the potatoes are cooked through.
Once cooked, give the dish a gentle stir. Adjust seasoning if necessary. Serve hot, garnished with fresh parsley.