Preheat oven to 450-f degrees. Place first dough in baking dish and form to your liking.
Combine flour and sugar in a separate bowl. Add 1/4 of mix to the bottom of your pie crust. Add chopped rhubarb then add the rest of your flour/sugar mixture. Break up butter into small pieces and dot on top of rhubarb.
Cut top piece of pie crust into strips to create a lattice pattern on top of pie. Brush top pie crust with egg wash (1 egg with 1 tsp water).
Bake for 15 minutes on lowest rack. Reduce temperature to 350-f degrees and bake for 40-45 minutes. Drape pie loosely with tin foil once crust has browned to your liking to avoid burning.
Serve warm with vanilla ice cream or at room temperature. Now go eat!