Preheat oven to 300 degrees.
Line a 9×9 baking pan with parchment and set aside.
In a small bowl, combine the all-purpose flour, whole wheat pastry flour, and salt. Set aside.
Cream the butter and granulated sugar for the cookie bars together. This should only take a minute.
Add in your egg and vanilla. Mix to combine. Add in your flour mixture and again, mix to combine.
Put it into your parchment-lined pan and press to even out.
Place in the oven and bake for about 17 minutes.
Remove from the oven and allow it to cool for 5 minutes.
Then, using the parchment paper, remove from the pan and set on a cooling rack. Cool them for another 25-30 minutes.
While they are cooling, mix your icing
Add your powdered sugar, vanilla, and butter to a bowl. Add in 2 tablespoons of milk to start
Mix well, than add in more milk if needed. I like my icing on the thick side, so it was good for me.
Spread over your cooled bars, then sprinkle generously with your patriotic sprinkles.
These are delicious served right away. They also hold really well for several days in the fridge too. They don't last long here, but have been good for up to 3 days.
They are best in an airtight container or wrapped with saran wrap.
Now, sit back and enjoy. You deserve it!