In a large bowl combine chicken, both cheeses, salsa, diced tomatoes, and cumin. Mix well to combine.
Unroll pie crusts onto a flat surface, and using a 4 inch cutter cut out 6 circles.
Divide chicken mixture into equal portions and place each portion on top of the pie crusts. Fold crusts over and pinch the edges together to seal. Using a fork crimp the edges of the pinched crusts to make hash marks to make sure they are sealed.
Put empanadas on a baking sheet, and using a knife make a couple small slits in the top of them to allow steam to escape while they cook.
(if desired) Brush with egg wash and place into preheated oven, baking for 15 minutes or until crust is a golden brown. May be served with sour cream or salsa.