In a large bowl, mix the flour, salt, and baking powder.
Cut in the chilled butter until the mixture resembles coarse crumbs.
Beat the egg and add it to the mixture, then gradually add cold water until a dough forms. You may need a bit more or less water.
Knead the dough gently on a floured surface until smooth. Wrap in plastic wrap and refrigerate for at least 30 minutes.
Heat olive oil in a large skillet over medium heat.
Add the chopped onion and cook until translucent.
Stir in the minced garlic and cook for another minute.
Add the ground beef and cook until browned, breaking it up with a spoon.
Stir in the paprika, ground cumin, black pepper, and salt. Cook for a few more minutes.
Remove from heat and mix in the sliced green olives, raisins, hard-boiled eggs, and grated cheese (if using). Let the filling cool.
Preheat your oven to 375°F (190°C).
On a floured surface, roll out the dough to about 1/8-inch thickness.
Cut out circles of dough using a cookie cutter or a glass (about 4-5 inches in diameter).
Place a spoonful of filling in the center of each dough circle.
Fold the dough over the filling to form a half-moon shape and press the edges together to seal. You can crimp the edges with a fork for a decorative touch.
Place the empanadas on a baking sheet lined with parchment paper.
Brush the tops with beaten egg to give them a golden color.
Bake for 20-25 minutes, or until the empanadas are golden brown and crispy.
Allow the empanadas to cool slightly before serving.
Enjoy your meal!