1 tbs milk
2 ½ cups (10 oz) sifted flour
½ tsp kosher salt
1 tsp baking powder
1 stick butter cut into small pieces
1 tbs cider vinegar
1/3 cup ice water
1 ¾ cup grated gouda
4 tbs Chopped chives
Whisk egg and milk, set aside. Add flour, salt and baking powder to a food processor, pulse until combined. Add butter vinegar and egg mixture and pulse again until mixture resembles course crumbs. With the food processor running, slowly add water and process until mixture just comes together (add a little more water if dough seems dry). Dump onto a lightly floured board and form a disk. Wrap in plastic wrap and rest in fridge for 1 hour.
Divide dough in half. Roll one half out to 1/8” thickness on a lightly floured surface and using a round 4” cookie cutter, cut out 8-10 disks. Place one disk in the palm of your hand and put some cheese and chives in the center. Fold disk in half and pinch the edges together to seal closed, being careful not to catch any filling in the seal. Use the tongs of a fork to create a decorative edge and a second seal. Refrigerate covered with plastic wrap for 30 minutes or up to 4 hours. Repeat with second half of dough.
Place enough vegetable oil in a pan to cover empanadas at least half way and heat to 375 using a candy thermometer. Place a few empanadas in oil and fry until golden brown, flipping for even color. Drain on paper towel and fry remaining empanadas. Serve immediately with chimichurri sauce if desired