In 1 & 1/2 to 2-quart saucepan, melt butter over medium heat. Stir in 2 tablespoons corn flour and 1 tablespoon all-purpose flour. Cook until bubbly, stirring frequently. Stir in remaining filling ingredients. Bring to a full rolling boil. Boil 1 minute, stirring constantly. Pour into bowl. Cover; refrigerate at least 30 minutes or until cooled.

When filling is cool, heat oven to 375°F. In large bowl, mix 1 & 3/4 cups all-purpose flour, 1/2 cup corn flour and salt until well mixed. Cut in shortening with pastry blender or 2 knives until mixture is crumbly. Stir in egg yolk and ice water until mixture sticks together. If necessary, sprinkle in 1 more tablespoon of water. Spoon dough onto floured work surface. Bring together into a smooth ball. Divide into 8 equal parts. On floured surface, roll each into 6-inch circle. Spoon 3 tablespoons of the corn mixture on each circle. Brush outside edges with egg white. Fold over and press edges to seal. Place on 2 small or 1 large ungreased cookie sheet(s). Crimp edges with fork. Sprinkle with coarse sugar. Bake 20 to 25 minutes or until golden brown. Cool on pan 10 minutes. Remove to cooling rack. Serve warm or cool.