Heat the olive oil in a large skillet over medium heat. Add the cubed beef and cook until browned on all sides. Remove the beef from the skillet and set it aside.

In the same skillet, add the onion, carrots, and celery. Cook until the vegetables are softened, about 5 minutes. Add the garlic and cook for another minute.

Sprinkle the flour over the vegetables and stir to coat. Slowly pour in the beef broth, stirring constantly to avoid lumps. Add the Worcestershire sauce, thyme, salt, and pepper. Bring the mixture to a simmer and cook until it thickens, about 5 minutes.

Return the beef to the skillet and add the frozen peas. Stir to combine and cook for another 2-3 minutes. Remove from heat and let the filling cool slightly.

Preheat your oven to 375°F (190°C). Roll out the puff pastry and cut it into circles large enough to cover the tops of your ramekins or muffin tins.

Divide the beef filling evenly among the ramekins or muffin tins. Place a puff pastry circle over each ramekin, pressing gently to seal the edges. Brush the tops with the beaten egg for a golden finish.

Place the ramekins on a baking sheet and bake for 20-25 minutes, or until the pastry is golden brown and puffed. Let the pot pies cool for a few minutes before serving.