1. Preheat your oven to 200°C (400°F).
2. In a skillet, heat olive oil over medium heat. Add the chopped onion and cook until translucent.
3. Add the garlic and cook for another minute.
4. Add the diced beef and cook until browned on all sides.
5. Stir in the mushrooms and cook until they release their moisture.
6. Sprinkle the flour over the mixture and stir well to combine.
7. Gradually add the beef broth, stirring continuously until the mixture thickens.
8. Add thyme, salt, and pepper. Let the mixture simmer for 10 minutes.
9. Pour the beef and mushroom mixture into a pie dish. Cover with the pie crust, sealing the edges.
10. Make a few slits in the crust to allow steam to escape.
11. Bake in the preheated oven for 30-35 minutes, or until the crust is golden brown.
12. Let the pie cool for a few minutes before serving.