Heat oil in a large skillet over medium heat; add onion and cook until browned, about 5 minutes. Add tomato paste, water, raisins and brown sugar and cook until mixture is very thick, stirring often. Stir in chicken, TABASCO® Chipotle Sauce and salt. Set aside to cool completely.
Preheat oven to 400°F. On a lightly floured surface, carefully unfold pie crusts according to package instructions and press or roll out to an 11- to 12-inch circle; cut out eight 3 1/2-inch circles from each crust (for a total of 32 circles). Spoon about 1 tablespoon filling onto each circle.
With a pastry brush dipped in cold water, lightly paint edges of each circle; fold over and press edges together with a fork. Place on a lightly greased baking sheet or one lined with parchment paper. (If you have time, slide empanadas into freezer for 30 minutes to ensure dough won't shrink when baked.) Repeat with remaining dough and filling.
Stir together egg and milk in a small bowl and lightly paint onto tops of empanadas, being careful not to let it run down onto baking sheet (it will make them stick). Bake until golden, about 15 to 18 minutes. Serve warm or at room temperature.