In medium bowl, toss together cheese and scallions.
On lightly floured work surface, using rolling pin, roll out disco until about ½” larger in diameter. Spoon 1 tablespoon cheese mixture into middle of dough. Moisten edges with water and fold in half to form half-moon shape. Twist edges to seal. Repeat with remaining discos and filling to make 10 empanadas.
Heat 2” oil in large, heavy pot over medium-high heat until oil registers 350°F on deep-fry thermometer. Alternately, heat oil in deep fryer to 350°F. Fry empanadas in batches until dough is crisp and golden brown and cheese is melted, about 5-6 minutes per batch. Transfer empanadas to paper towels to drain. Sprinkle with sugar before serving, if desired. Serve with hot sauce, if desired. Serve warm.