Cook the bacon: Fry the bacon until crispy, then drain on paper towels. Once cool, crumble into small pieces.
Preheat oven: Heat to 180°C (350°F) and line a baking sheet with parchment paper.
Prepare the pastry: Lightly dust your work surface with flour. Roll out the puff pastry into a large rectangle, about ¼ inch thick (roughly the thickness of a £1 coin). Trim edges for straight sides.
Add the filling: Spread tomato paste evenly over the pastry, leaving a 1 cm border. Sprinkle bacon evenly over the surface, then add both cheeses.
Roll and seal: Starting from one long edge, roll the pastry tightly into a log. Brush the edge with beaten egg to seal.
Slice and prep: Cut the roll into 2 cm thick slices and place flat on the baking sheet. Brush tops with remaining egg wash.
Bake: Cook for 15–20 minutes, or until puffed, golden, and bubbling with cheese.
Serve warm: Enjoy fresh out of the oven as a party snack or appetizer.