Frosted Brown Sugar Pop Tart Bars

1. To make the cookie dough. In a bowl using an electric mixer, beat together the flour, sugar, and butter. Add the vanilla and 1/3 cup cold water. Beating until just combined, adding 1-2 tablespoons additional water as needed until the dough forms a ball. 3. Preheat the oven to 350° F. Line a 9×9 inch baking dish with parchment paper. 4. Divide the dough in half. Press half the dough into the prepared baking dish. Trace the 9x9 inch baking dish out on a sheet of parchment paper. Now, roll the remaining dough out just past the edges of the traced-out square. Set aside.5. To make the filling. Combine all ingredients in a bowl. Evenly spread the filling dough into the baking dish. Carefully invert the reserved dough square over the filling, pressing down gently to secure. Trim away any excess dough. 6. Freeze the bars for 15 minutes. Bake for 40 - 45 minutes, until just set in the center. Let cool.7. To make the frosting. In a bowl, whisk together all of the ingredients and 1-2 tablespoons of water until smooth. If your frosting is too thick, thin with 1-2 tablespoons of additional water.8. Spread the frosting over the pop-tart bars. Let set a few minutes, then top with salt/sugar (optional). Let dry, then cut into bars. Serve or store in an airtight container for up to 3 days at room temperature.