Peel yucca and place in a pan. Cover with water, bring to a boil and cook until yucca is tender.
Remove pan from heat. Place yucca in a bowl and mash it with a potato masher until smooth. Incorporate melted butter, egg yolks, parmesan cheese and baking powder, mixing thoroughly by kneading with both hands.
Divide dough in two. Roll out one half on a floured work surface. With a round cookie cutter (3 inches - 6 cm) cut circles.
Place a small amount of cheese in the center of each circle and fold each one in half. Seal by pressing both ends together with your fingers.
Repeat with the rest of the dough. Refrigerate for ½ hour.
Before serving heat oil until hot, flour the pastries lightly and fry until golden.
Remove and drain on paper towels. Serve 2 or 3 as an entrée.
Can be served as appetizers as well.
Yields 30 yucca empanadas