Instructions:
- In a bowl, toss the beef cubes with flour, salt, pepper, paprika, and onion powder until lightly coated. (Optional: Sear cubes in batches until browned on all sides, then set aside.)
- Place the seasoned (and optionally seared) beef cubes into the slow cooker insert.
- Pour in the beef broth and Worcestershire sauce. Tuck the thyme sprigs and bay leaves amongst the meat. Do not stir yet.
- Scatter the quartered potatoes evenly over the top of the beef and liquid mixture. Crucially, do not stir them under the liquid.
- Cover and cook on LOW for 7-8 hours or on HIGH for 3-4 hours, until the beef is fork-tender.
- About 30 minutes before serving, remove the lid. Discard the bay leaves and thyme stems. Stir in the minced garlic and the cold cubes of butter until melted and incorporated, creating a glossy sauce.
- If the sauce is too thin, remove the lid and switch the slow cooker to HIGH for the last 15-20 minutes to allow some liquid to evaporate.
- Taste and adjust seasoning as needed. Garnish generously with fresh parsley before serving directly from the pot.