In a large skillet over medium-high heat, heat olive oil. Add steak slices and cook until browned, about 2 minutes per side. Transfer steak to plate and set aside.
Add onions and garlic to skillet. Cook, stirring often, until onions are softened and golden brown, about 10 minutes. Add thyme and cook for 1 minute.
Add beef broth, Worcestershire sauce, salt, and pepper to skillet. Bring to a boil, then reduce heat to low and simmer for 10 minutes.
In a small saucepan, melt butter over medium heat. Add flour and whisk until lightly browned, about 2 minutes. Slowly whisk in wine, then cook for 3 minutes until thickened. Add this mixture to the soup and stir to combine.
Add parmesan, gruyere, and steak to soup. Simmer for 5 minutes.
Add parsley and French bread cubes to soup. Simmer for 5 minutes.
Serve hot.
Interesting Facts
French onion soup is a type of soup originating from France, made with beef broth and caramelized onions.
Ribeye steak is a cut of beef from the rib section.
Gruyere cheese is a Swiss cheese made from cow's milk.