In food processor add your flour and sugar and pulse to combine. Add your butter and pulse again until it comes together. Add your vanilla and turn on and slowly add your water.
Ball up your dough and cover and chill for at least 20-30 minutes.
Once chilled, sprinkle flour over a clean work surface and roll out your dough into a large 1/4" thick rectangle. Cut out with stencil or whatever you have on hand and cut into a pop tart shape, removing excess dough. Make 12-16 rectangles, you may have to roll out leftover dough.
Pre-heat oven to 400.
Mix together your egg wash ingredients, set aside,
Spray a baking sheeet with non stick cooking spray and cover with parchment paper or a silpat mat.
Place about 6-8 of your dough cut outs on baking sheet and brush with your egg wash. Sprinkle about 1 tablespoon of your filling mixture over the center of your dough and spread out to about 1/4" from your sides. Place your remaining dough rectangles on top of filing and crimp sides with fork to seal. Poke about 10 holes in top with toothpick to vent.
Bake for about 15 minutes or until golden and remove from oven to cool.
Meanwhile make your icing by mixing your powdered sugar, milk and cinnamon in a bowl until smooth. Add in more milk or powdered sugar to get your desired consistency.
One pop tarts are cooled spread your icing over the top and let rest to set up and harden for about 15 minutes.