Preheat the oven to 350°F.
Line a rimmed baking sheet with parchment paper.
In the bowl of a stand mixer, combine flour, sugar, baking powder, and salt. Add 2 eggs, the melted butter, and vanilla.
Mix at low speed until the dough becomes incorporated. Add the Sun-Maid Dried Mixed Berries and mix until combined.
Transfer the dough to a lightly floured surface.
Knead a few times, then divide it in half.
Shape each half into a 1-inch-thick rectangle and place on the baking sheet at least 4 inches apart.
Beat the remaining egg and brush it over the dough.
Bake until dough is lightly browned, about 30 minutes. Transfer the loaves to a wire rack and let cool about 20 minutes (If you attempt to cut the cookies while the dough is still hot, they will fall apart). Reduce the oven temperature to 325°F.
With a serrated knife, cut the short-side of each loaf into ¾ inch-wide slices. Transfer the slices back to the baking sheet, and bake for another 20 minutes, flipping halfway through, or until lightly browned and cookies appear dry.
Transfer to a wire rack and let cool completely. Store in an airtight container for up to one month.
