Heat the olive oil in a large skillet over medium heat. Add the chopped onion and sauté until translucent, about 5 minutes.
Add the minced garlic and sliced mushrooms to the skillet. Cook for another 5-7 minutes until the mushrooms are browned and tender.
Season the sliced beef with salt and pepper. Add the beef to the skillet and cook for 3-4 minutes until it browns, stirring frequently.
Sprinkle the flour over the beef mixture, stirring to coat. Cook for an additional minute.
Gradually add the beef broth and Worcestershire sauce, stirring constantly. Bring it to a simmer and cook for about 5-7 minutes until the sauce thickens.
Remove the skillet from the heat and stir in the sour cream until fully combined.
Preheat the oven to 400°F (200°C). Arrange the slices of French bread on a baking tray.
Spoon the beef stroganoff mixture generously over each slice of French bread.
Bake in the preheated oven for 10-12 minutes until the edges of the bread are crispy.
Remove from the oven and garnish with fresh parsley before serving.