1. Heat oil in heavy saucepan until it registers 375 degrees F on a deep-fry thermometer. Line a 15 x 10-inch baking pan with a double layer of paper towels. Heat oven to 200 degrees F.
2. In medium-size bowl, whisk together flour, cornstarch, baking powder, cinnamon and salt. Set aside.
3. In a large bowl, beat together cheese, butter, eggs and sugar until blended, about 2 minutes. Stir in flour mixture to make a soft dough. Roll rounded teaspoonfuls into balls.
4. Carefully slip 6 to 8 balls into heated oil. Fry 3 to 4 minutes per batch, until nicely browned. Remove with a slotted spoon. Transfer to paper-lined pan. Sprinkle each batch with 1 teaspoon cinnamon-sugar. Keep bunuelos warm in 200 degrees F oven while repeating. Serve slightly warm.