Place blueberries in a small sauce pan. Add 1/4 cup Stevia in the Raw, 1/4 cup Sugar in the Raw Organic White, 2 Tablespoons cornstarch and 2 Tablespoons of water. Set saucepan over medium low heat and simmer, stirring occasionally, until fruit is soft and mixture is thickened; about 20 minutes.
Repeat process with the raspberries and remaining Stevia in the Raw, Sugar in the Raw Organic White, cornstarch and water.
Allow fruit mixtures to cool before forming the pop tarts.
Preheat oven to 425 degrees. Line a rimmed baking sheet with parchment paper and set aside.
Roll out one pie crust to 1/8 inch thickness. Cut crust into 9 - 2x3 inch rectangles and place on prepared baking sheet. Add 1 Tablespoon of fruit mixture in the center of each piece of dough. Roll and cut second crust in the same manner as the first, and place the rectangles on top of the fruit mixture. Use a fork to crimp the edges of the pop tarts. Bake for 10-12 minutes or until crust is golden brown. Remove from oven, transfer pop tarts to a wire rack to cool completely.