Preheat oven to 400 degrees.
In a bowl, mix chicken, cream cheese, garlic, green onion, cumin, black pepper, salt, cheddar and Monterey jack cheese.
Prepare egg wash by beating egg yolk with water.
Unroll frozen pie crust on floured surface and cut into 5 inch circles.
Drop about 2 tablespoon of the mixture into the center of the circle then brush around the edges with egg wash.
Fold in half and press the edges with a fork to seal.
Place on a baking pan and brush the tops with the egg wash.
Place in preheated oven and bake for 15 minutes until golden brown. Remove from the oven and place on a baking rack to cool.