Preheat your oven to 200°C (390°F).

Finely chop or pulse the onion in a food processor until it’s very small, then sauté it in a little oil over medium heat until soft and fragrant.

In a mixing bowl, combine the beef mince, sautéed onion, panko breadcrumbs, minced garlic, crumbled beef stock cube, salt, black pepper, jalapeños, cheddar, and parmesan. Mix thoroughly.

Beat the medium egg and add it to the mixture, then blend until everything is well combined.

Roll out one sheet of puff pastry on a floured surface. Cut it in half lengthwise.

Spoon a generous portion of the beef mixture along one edge of the pastry and roll it up tightly. Seal the edges using a little water or the separated egg white.

Repeat with the second sheet of pastry and remaining filling.

Once rolled, cut each log into individual sausage rolls (about 4-5 pieces) and place them on a lined baking tray.

Brush the tops of the sausage rolls with the beaten egg and sprinkle with sesame seeds.

Bake in the preheated oven for 20-25 minutes, or until golden brown and puffed.

Remove from the oven and allow to cool slightly before serving.