Prepare the Filling: Place a large frying pan over medium-high heat. Add the beef mince and cook, breaking it up with a wooden spoon, until it is deeply browned and no longer pink. You should hear a steady sizzle and smell the meat toasting. Drain off any excess fat, leaving about a tablespoon in the pan.

Build the Flavour Base: Reduce the heat to medium. Add the diced onion and red bell pepper to the pan. Cook, stirring often, until the onion becomes soft and translucent, about 5-7 minutes. The vegetables will look glossy and the raw onion smell will mellow into a sweet aroma. Add the minced garlic, cumin, smoked paprika, oregano, and chilli flakes, if using. Stir continuously for 1 minute until the spices become fragrant and coat the meat.

Simmer the Mixture: Stir in the tomato paste and cook for another minute. The paste will darken slightly in colour. Pour in the beef stock, scraping the bottom of the pan with your spoon to lift any browned bits. Let the mixture simmer gently for 5-7 minutes, or until most of the liquid has evaporated. The filling should look moist but not wet or sloppy. You'll see it holding its shape when you push it with the spoon.

Finish the Filling: Remove the pan from the heat. Allow the mixture to cool for at least 10 minutes. This is a crucial step. Once slightly cooled, stir in the chopped hard-boiled eggs and the grated cheese. Taste and adjust the seasoning with salt and pepper. The cheese will look like soft, bright strands mixed through the warm, dark beef.

Assemble the Empanadas: Preheat your oven to 200°C (400°F). Line a baking sheet with parchment paper. Place an empanada disc on a clean work surface. Spoon about 2 tablespoons of the filling onto the centre of the disc. Be careful not to overfill, or they will burst open. Lightly brush the edges of the disc with the beaten egg wash.

Seal and Crimp: Fold the disc in half to create a half-moon shape, pressing the edges firmly to seal. To crimp, you can press the edges with the tines of a fork, or for a traditional repulgue, start at one end and fold the edge over itself, pinching as you go. The seal will look tight and uniform. Place the assembled empanada on the prepared baking sheet. Repeat with the remaining discs.

Bake to Golden Perfection: Brush the top of each empanada generously with the remaining egg wash. This will give them a beautiful, shiny glaze. Bake for 20-25 minutes, rotating the tray halfway through. The empanadas are ready when the pastry is a deep, rich golden brown and feels firm and crisp to the touch. You might see a tiny bubble of filling escape if one wasn't sealed perfectly.

Rest and Serve: Remove the baking sheet from the oven. Let the empanadas rest on the tray for 5 minutes before serving. This allows the hot filling to settle. The pastry will be shatteringly crisp as you bite into it.