In a large mixing bowl, combine flour with a pinch of salt. Cut in cold butter using a pastry cutter until the mixture resembles coarse crumbs. Gradually add cold water until the dough holds together, then form it into a ball. Wrap the dough in plastic wrap and chill in the refrigerator for 30 minutes to enhance flakiness.

While the dough chills, heat a skillet over medium heat. Sauté the onion until translucent, about 5 minutes. Add ground beef and cook until browned, stirring occasionally. Stir in minced garlic, chopped olives, and spices until well combined. Allow the mixture to cool.

Preheat your oven to 350°F (175°C). Flour a clean surface and roll out the chilled dough to about 1/8 inch thickness. Use a round cutter to cut out circles, 4-5 inches in diameter. Place a spoonful of the cooled beef filling in the center of each circle and fold over the dough, crimping the edges with a fork to seal.

Arrange filled empanadas on a baking sheet lined with parchment paper. Brush the tops with melted butter for added crispiness. Bake for 25-30 minutes or until golden brown.

Once baked, remove empanadas from the oven and let them cool on a wire rack for a few minutes. Serve warm, perhaps with a dipping sauce or a light salad.