Heat the olive oil in a large skillet over medium heat.
Add the sliced onions and cook, stirring frequently, for about 15-20 minutes until they are golden brown.
Stir in the minced garlic and cook for an additional 2-3 minutes until fragrant.
Push the onion and garlic mixture to one side of the skillet, then add the ground beef to the other side.
Once the beef is browned, mix it with the onions and garlic, then sprinkle flour over the mixture (if using).
Pour in the Worcestershire sauce and beef stock, then stir to combine.
Add salt, pepper, and dried thyme; taste and adjust seasoning as needed.
Bring the mixture to a boil, then reduce heat and let it simmer for about 10-15 minutes.
Serve hot over your choice of side, such as mashed potatoes or crusty bread.
