Dust a rolling pin with flour and begin to roll out the dough, rotating it 1 inch after every 1-2 rolls. This will help ensure the dough doesn't stick to the counter, and will also keep it in a round shape. Use a measuring tape or the pie plate to determine when the dough has reached the right circumference. It should measure about 3 inches larger than the pie plate. If the dough doesn't roll out perfectly round, use a knife or a pizza cutter to trim the edges and even it out.

Carefully roll the dough onto the rolling pin and use it to transfer to a 9-inch pie plate, then gently press it in to fit.

Pour the blueberries over the crust, then dot the top with 2 tablespoons butter. Remove the second disc from the fridge and roll out the same way as the bottom. If desired, you can use a small cookie cutter to cut out some fun shapes in the crust at this point, or you can wait and cut slits right before baking.

Use the rolling pin to transfer it over top to cover the filling. Use your fingers to pinch together the edges of the top and bottom crust to seal in the filling, then use a pair of kitchen shears to snip off any excess, leaving about 1 inch of overhang on all sides.

Tuck and roll the overhang under, then use your fingers or a fork to crimp the edges. Cut a few slits to vent the top if you didn't cut out shapes, then brush all over with the egg wash. Sprinkle with coarse sugar if desired, then bake until the crust is deep golden brown and the filling is bubbling, about 1 hour or longer.

Allow the pie to rest for at least 30 minutes, but 1-2 hours is better. Cut into slices and serve warm with vanilla ice cream.