01 - In a large mixing bowl, whisk together gluten-free flour blend, salt, and baking powder until well blended.
02 - Add cubed cold unsalted butter. Cut into flour using a pastry cutter or fork until mixture forms coarse crumbs.
03 - Add 1 large egg, apple cider vinegar, and cold water. Stir until dough just forms. If crumbly, add cold water one tablespoon at a time until cohesive.
04 - Shape dough into a disc, wrap in plastic, and chill in the refrigerator for 30 minutes.
05 - Heat olive oil in a skillet over medium heat. Add chopped onion and minced garlic; cook for 3 minutes until softened.
06 - Stir in diced red bell pepper, ground cumin, smoked paprika, dried oregano, chili powder, salt, and black pepper. Cook for 2 minutes.
07 - Mix in shredded chicken breast and tomato sauce. Cook until heated and slightly thickened, about 3–4 minutes. Remove from heat, then add chopped green olives and fresh cilantro or parsley. Cool to room temperature.
08 - Set oven to 400°F. Line a baking sheet with parchment paper.
09 - On a lightly floured surface, roll dough to 1/8-inch thickness. Cut out 4- to 5-inch circles using a round cutter or glass.
10 - Place 2 tablespoons chicken filling in the center of each dough circle. Fold over to create a half-moon shape. Press edges to seal and crimp with a fork.
11 - Arrange filled empanadas on the prepared baking sheet. Beat remaining egg and brush lightly over tops.
12 - Bake empanadas for 20 to 25 minutes or until golden brown. Cool briefly before serving.