In a medium bowl, whisk together 1/2 cup whole grain pastry flour, 1/2 cup spelt flour, 3 tablespoons granulated sugar, 3 tablespoons dark brown sugar, 1/2 teaspoon baking powder, 1/2 teaspoon ground cinnamon, and 1/4 teaspoon kosher salt until well combined. Use your fingers to rub the 3 tablespoons cubed, cold butter into the flour mixture, breaking it into smaller bits and making sure that all of the bits are coated. Continue rubbing until the mixture feels coarse and you're left with pea-sized crumbles. The faster you do this, the better (or everything gets all melty and gross).