In a large skillet over medium-high heat, melt 2 tablespoons of butter.
Add the beef bites to the skillet and sear for about 3-4 minutes until browned on all sides. This step enhances the flavor but can be skipped if you're short on time.
Transfer the beef bites to the slow cooker.
In the same skillet, add the remaining 2 tablespoons of butter and minced garlic. Sauté for 1-2 minutes until the garlic is fragrant but not browned.
Pour the garlic-butter mixture over the beef in the slow cooker.
Add chopped rosemary, thyme, black pepper, salt, beef broth, soy sauce, and Worcestershire sauce to the slow cooker.
Stir the ingredients gently until the beef is evenly coated.
Cover and cook on low heat for 6-7 hours or on high heat for 3-4 hours until the beef is tender.
If you prefer a thicker sauce, mix cornstarch with a little cold water to create a slurry, and stir it into the slow cooker about 30 minutes before finishing the cooking time.
Taste and adjust seasoning if needed.
Notes
Serve over mashed potatoes or rice, garnished with parsley.