In a large bowl, combine sugar and butter.
Using the paddle attachment, mix sugar and butter until very creamy.
Add egg and blend until thoroughly combined.
Add vanilla and mix until thoroughly incorporated.
Combine all purpose flour, whole wheat flour, baking powder and cinnamon in a separate bowl.
Add dry ingredients to batter, a little at a time, until thoroughly combined.
This makes a dense sugar cookie dough.
Place hamantaschen dough in refrigerator for at least an hour so that the dough will be easier to roll out without sticking.
Preheat oven to 350 F.
Place a piece of parchment paper on a baking sheet or spray generously with cooking spray.
Divide dough in half.
On a lightly floured surface, roll out one half of the dough. Keep the other half refrigerated while you work with one half.
Roll dough as thin as possible. Using a round cookie cutter, cut out circles (you can use whatever size you prefer). Place about a teaspoon of the preserves in the center of each circle.
Rub the perimeter of the cookie with a little water.
Fold in the sides to make triangular cookies.
Continue to repeat rolling out the excess dough after you cut out the cookies, until all the dough has been utilized.
Repeat with the other half of the dough.
Place on parchment lined baking sheets an inch apart.
Bake for 15-20 minutes, until golden brown.