• Preheat the oven to 425° F and place a rimmed baking sheet inside to heat.

Make the Pie Crust

• Prepare the pie dough according to recipe directions. Divide into two portions, one slightly larger than the other, and shape into discs. Wrap and refrigerate for 20 minutes.

Make the Filling

• While the dough chills, make the filling by combining the rhubarb, 1 cup sugar, brown sugar, flour, orange zest, and vanilla in a large bowl. Toss until the rhubarb is evenly coated.
  6 cups rhubarb, 1 cup sugar, 1/4 cup brown sugar, 5 Tablespoons flour, 1 teaspoon orange zest, 1/2 teaspoon vanilla extract
• Roll out the larger disc on a lightly floured surface until it is about 1 inch larger than your pie dish. Transfer to the dish and gently press into place. Refrigerate while you roll the top crust.
  0.5 recipe pie dough
• Roll out the second disc for the top crust.
  0.5 recipe pie dough
• Remove the pie dish from the refrigerator and pour in the rhubarb filling. Dot the top with butter.
  2 Tablespoons butter
• Brush the edges of the crust with water, place the top crust over the filling, trim excess, and crimp to seal. Cut several vents in the top.
• Whisk the egg with a splash of water to make an egg wash. Brush over the crust and sprinkle with the remaining tablespoon of sugar.
  1 egg, 1 Tablespoons sugar
• Place the pie on the hot baking sheet and bake for 45 minutes, checking for browning. If needed, loosely cover with foil.
• Reduce the oven temperature to 375° F and continue baking for 20 minutes, until the filling is bubbling.
• Cool for 3–4 hours before slicing to allow the filling to set.