In a large skillet over medium-high heat, cook ground beef, chopped onion, garlic powder, salt, and black pepper until beef is browned and no pink remains, about 5 to 6 minutes.
Transfer beef mixture to a paper towel-lined plate and drain excess fat from the skillet.
Reduce heat to medium and melt butter in the skillet.
Whisk in flour until smooth to create a roux.
Slowly pour in beef broth while whisking to prevent lumps.
Add Better than Bouillon and Worcestershire sauce, whisking to dissolve, then let the gravy simmer and thicken for 3 to 5 minutes.
Stir in milk and whisk until the gravy is smooth.
Lower heat to low, return the cooked beef mixture to the skillet, and simmer the gravy until thickened, about 5 more minutes.
Remove from heat and garnish with chopped fresh parsley if desired.