01 - Preheat the oven to 400°F. Line a baking tray with parchment paper and set aside.
02 - Heat olive oil in a frying pan over medium-high heat. Add the chopped onions and cook for 2 minutes until softened. Add the minced garlic and cook for 30 seconds until fragrant.
03 - Add the diced steak to the pan and fry until browned on all sides, about 3 minutes. Stir in the Worcestershire sauce and season with salt and black pepper.
04 - Sprinkle the flour over the steak mixture and stir well to coat. Pour in the beef stock and cook for 2 to 3 minutes until the liquid thickens into a glossy sauce. Remove from heat and let cool slightly, then stir in the grated cheddar until melted and evenly combined.
05 - Unroll the puff pastry onto a lightly floured work surface. Using a sharp knife, cut the sheet into four equal rectangles.
06 - Spoon equal portions of the steak and cheese filling along one long edge of each pastry rectangle. Brush the pastry edges with beaten egg, fold the pastry over the filling, and press firmly to seal. Place each roll seam-side down on the prepared baking tray and crimp the edges with a fork to secure.
07 - Cut a few small slits in the top of each roll to allow steam to escape during baking. Brush the tops generously with the remaining beaten egg for a golden finish.
08 - Bake in the preheated oven for 20 to 25 minutes until the pastry is puffed, golden brown, and crisp. Allow to cool slightly before serving.