Reserve the white of one egg for glazing; refrigerate. Combine 2 cups (500 mL) of the flour with baking powder, cinnamon and salt; set aside.
In a large bowl with mixer at medium speed, beat peanut butter, butter, brown sugar, corn syrup, 2 eggs and remaining egg yolk until smooth. Blend in flour mixture. Stir in remaining 2 cups (500 mL) flour. Wrap dough in plastic wrap; refrigerate at least 3 hours or overnight.
Preheat oven to 325 F (160°C). Lightly beat reserved egg white with fork. On floured surface, roll out one third of the dough to 1/8 inch (3 mm) thickness. Cut with floured star-shaped cookie cutter. Place on ungreased baking sheets. Brush cookies with beaten egg white; sprinkle with granulated sugar. Repeat with remaining dough. Bake 12 to 15 minutes or until lightly browned. Remove from baking sheets; cool completely on wire rack.