Season the cube steaks with salt, black pepper, and garlic powder. Lightly coat both sides with 1 tablespoon of the flour.
Melt 2 tablespoons of the butter in a skillet over medium-high heat. Cook the steaks for 4–5 minutes per side, until browned. Remove the steaks from the skillet.
Add the remaining 4 tablespoons butter to the skillet and melt.
Whisk in the remaining 3 tablespoons flour and cook for 1 minute.
Whisk in the beef broth and Worcestershire sauce until smooth.
Stir in the sliced onion and cook for 5–6 minutes, until tender and the gravy has thickened.
Return the steaks to the skillet and spoon the gravy over the top.
Reduce the heat to low, cover, and simmer for 5–7 minutes, until the steaks are cooked through.
Serve warm.
Notes
Refrigerate the leftovers in an airtight container for up to 5 days.