Make apple filling. In a medium sauce pan, combine sugar, water, cornstarch and cinnamon. Stir over medium heat and bring to boil. Cook 1 minute, then add in half amount of apple. Bring back to boil over medium-high heat and cook for 8 minutes, or until soft, stirring often. Add remaining apples and cook for another 6 minutes. Remove from heat, add butter and stir to dissolve. Set aside.