Combine 2 cups all-purpose flour and 1/2 tsp salt in a mixing bowl, then cut in 1/2 cup chilled, cubed unsalted butter until mixture resembles coarse crumbs.

Gradually add 1/4 cup cold water and mix until dough just comes together; do not overwork.

Wrap dough in plastic wrap and refrigerate for at least 30 minutes to firm the butter.

In a skillet over medium heat, sauté 1/2 cup finely chopped onion and 1/2 cup finely chopped bell pepper until soft, about 5 minutes.

In a bowl, combine the sautéed vegetables with 1 lb shredded cooked chicken, 1 tsp garlic powder, 1 tsp cumin, 1/2 tsp paprika, and 1/4 tsp black pepper and mix well.

On a floured surface, roll out the chilled dough to about 1/8 inch thickness using a rolling pin.

Cut the dough into 4-5 inch circles using a knife or pizza cutter, then place a spoonful of filling in the center of each circle.

Fold each circle in half to form a half-moon, press edges together to seal, and crimp with a fork for a decorative seal.

Preheat oven to 375°F (190°C), line a baking sheet with parchment paper, place empanadas on the sheet, brush tops with beaten egg, and bake for 20-25 minutes until golden brown.