Start by blitzing the chorizo into a smooth paste using a food processor. In a skillet over medium heat, add 1 1/2 tablespoons of olive oil, and sauté finely chopped onions and minced garlic until soft, about 3-4 minutes. Add the beef mince to the pan, cooking until browned, approximately 5-7 minutes. Stir in the chorizo paste, tomato paste, and spices, then fold in the cubed potato. Pour in the chicken stock and tomato passata, simmering for about 15 minutes until the mixture thickens and the potatoes are tender. Allow the filling to cool for at least 2 hours.

In a food processor, pulse together 2 1/2 cups of flour, 1 teaspoon of salt, and 175g of cold unsalted butter until the mixture resembles coarse crumbs. Add 1 egg yolk and 1/2 cup of warm milk, pulsing until the mixture forms a dough ball. Wrap the dough in plastic wrap and chill in the refrigerator for 30 minutes to ensure it firms up and becomes easier to roll out.

Once the dough has chilled, remove it from the refrigerator and place it on a lightly floured surface. Roll out the dough to a thickness of about 3mm. Using a round cutter, cut out circles approximately 15 cm in diameter. Gather any scraps, reroll them, and continue cutting until you've made enough rounds for your beef empanadas.

Preheat your oven to 220°C (425°F). Take one dough round and place about 3 tablespoons of the cooled filling on one half. Sprinkle with chopped green olives and a piece of chopped hard-boiled egg. Brush the edges with the egg white, then fold the dough over the filling to meet the other half, pressing to seal. For an extra touch, create pleats along the edge to make the empanadas visually appealing.

Arrange the assembled beef empanadas on a lined baking tray. Brush the tops with the reserved egg yolk for a glossy finish. Bake in the preheated oven for 20 minutes or until the empanadas are golden brown and crispy. Keep an eye on them to ensure they don’t over-bake. Remove from the oven and allow to cool slightly before serving these delightful beef empanadas warm.