Sear the Beef:
Heat 2 tablespoons of butter and olive oil in a skillet over medium-high heat. Add beef cubes in batches and sear until browned on all sides (1–2 minutes per side).
Load the Slow Cooker:
Transfer the seared beef to your slow cooker. Add garlic, salt, pepper, paprika, onion powder, and thyme or rosemary.
Add Liquids:
Pour in beef broth and Worcestershire sauce. Stir gently to coat all the beef with flavor.
Cook:
Cover and cook on LOW for 6–7 hours or HIGH for 3–4 hours, until beef is tender and flavorful.
Finish with Butter:
About 15 minutes before serving, melt the remaining 2 tablespoons of butter and stir it into the slow cooker for a rich, glossy sauce.
Serve:
Garnish with chopped parsley and serve hot with mashed potatoes, rice, or roasted vegetables.