In a mixing bowl, combine the flour and salt. Add the cubed butter and mix until the mixture resembles coarse crumbs.

Gradually add cold water until the dough comes together. Shape it into a disk, wrap it in plastic wrap, and refrigerate for at least 30 minutes.

In a skillet, heat olive oil over medium heat. Add the chopped onion and cook until translucent, about 5 minutes.

Add minced garlic and cook for an additional minute.

Add the chicken to the skillet, season with cumin, paprika, black pepper, and salt. Cook until the chicken is no longer pink and cooked through, about 10-12 minutes. Remove from heat and let it cool slightly.

Once cooled, shred the chicken into smaller pieces and mix in the thawed peas.

Preheat the oven to 400°F (200°C). Roll out the chilled dough on a floured surface until about ⅛ inch thick.

Cut out circles using a large cookie cutter or a glass (about 4-5 inches in diameter).

Place a tablespoon of the chicken filling in the center of each circle. Fold the dough over the filling to create a half-moon shape and press the edges together to seal.

Use a fork to crimp the edges for an extra seal. Arrange the empanadas on a baking sheet lined with parchment paper.

Brush the tops with the beaten egg for a golden finish.

Bake in the preheated oven for 20-25 minutes or until the empanadas are golden brown.

Remove from the oven and let cool slightly before serving. Garnish with fresh cilantro if desired.