Cook the steak filling

• Heat the olive oil in a frying pan and brown the steak over high heat.
• Add the onion and mushrooms and cook until softened and golden.
• Season with salt and pepper and let the filling cool completely.

Shape the pop tarts

• Roll out the puff pastry and cut it into equal rectangles.
• Spoon the cooled filling and grated cheddar onto half of the rectangles, leaving a border.
• Top with the remaining rectangles, press the edges with a fork and brush with beaten egg.

Bake

• Place the pop tarts on a lined baking tray.
• Bake at 200 °C until puffed and golden.

Serve

• Let cool slightly before serving.