Place the peeled potatoes in a large pot of salted water. Bring to a boil and cook until tender, about 15 minutes. Drain thoroughly and mash while hot with butter and warm milk until smooth. Season with salt and pepper. Set aside while preparing the filling.

In a large pan, heat olive oil over medium heat. Add the onions, bell pepper, and garlic, cooking until softened and fragrant. Stir often to prevent burning and build a rich base of flavour.

Add the minced beef to the pan, breaking it apart with a wooden spoon. Cook until browned evenly. Season with paprika, cumin, oregano, salt, and pepper. Stir well so the spices coat the meat completely.

Add tomato purée and stir to combine. Reduce the heat slightly and simmer for 5–7 minutes until the mixture thickens and becomes glossy. This helps the filling hold together when layered.

Remove the pan from the heat and stir in the chopped boiled eggs and sliced olives. These classic Argentine touches bring depth and saltiness that balance the rich meat. Allow the filling to cool slightly before assembling.

Preheat your oven to 190°C (170°C fan). Grease a medium baking dish (around 20 x 20 cm). Spread half the mashed potatoes evenly across the bottom to form the base layer.

Spoon the meat mixture over the potato base, pressing gently to even it out. Ensure it reaches the corners of the dish so every bite is balanced.

Spread the remaining mashed potatoes evenly over the filling. Use a fork to create a decorative pattern on the surface, which helps the top crisp up in the oven.

Brush the top with beaten egg to give a golden finish. Bake in the preheated oven for 25–30 minutes, or until the surface is lightly browned and the edges are bubbling.

Let the pastel rest for 10 minutes before serving. This allows the layers to settle and makes slicing cleaner. Serve with a simple green salad or pickled onions for contrast.