01 - In a large mixing bowl, whisk together gluten-free flour blend, salt, and baking powder.
02 - Add cold cubed butter and cut into dry mixture using a pastry cutter or fork until a crumbly texture forms.
03 - Add 1 egg, apple cider vinegar, and 1/4 cup cold water to the bowl. Mix just until dough begins to come together, adding more water one tablespoon at a time if needed.
04 - Shape dough into a disc, wrap in plastic, and refrigerate for 30 minutes.
05 - Heat olive oil in a skillet over medium heat. Sauté onion and garlic until softened, about 3 minutes.
06 - Add diced red bell pepper, ground cumin, smoked paprika, oregano, optional chili powder, salt, and black pepper. Cook for 2 minutes, stirring occasionally.
07 - Stir in shredded chicken and tomato sauce. Cook until mixture is heated through and slightly thickened, about 3–4 minutes, then remove from heat. Fold in chopped olives and fresh cilantro or parsley. Allow filling to cool to room temperature.
08 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
09 - On a lightly floured surface, roll dough to 1/8-inch thickness. Using a 4- to 5-inch round cutter, cut dough into circles.
10 - Place 2 tablespoons chicken filling in the center of each dough circle. Fold in half to create a half-moon shape, sealing the edges by pressing firmly and then crimping with a fork.
11 - Transfer empanadas to lined baking sheet. Beat remaining egg and gently brush over tops for a golden crust.
12 - Bake in the preheated oven for 20–25 minutes, or until golden brown. Allow to cool briefly before serving.