Mix together ricotta cheese, Presto, sugar, eggs and vanilla. Pour corn oil into heavy, flat bottomed 3-quart pot or deep fryer, filling no more than 1/3 full. Heat over medium heat to 375°. Carefully drop dough by 1/2 teaspoons, 1 layer at a time into corn oil. Fry about 1 to 2 minutes or until well browned. Drain on paper towel. Sprinkle with confectioners' sugar.