Clean cherries and remove pits. Cut in half if you like. Measure 6 cups of cherries and put in a strainer and allow to drain over a bowl if your cherries are extra ripe.
In a small bowl, mix together the cornstarch, sugar, salt and cinnamon.
In a large bowl, mix together cherries and vanilla. Stir in sugar mixture and blend well.
Put the cherries in a 9" pie crust and top with second pie crust. Crimp edges and brush top of pie with the beaten egg. Sprinkle with sugar. Put several slices in the top of the pie crust to let the pie vent as it cooks.
Bake the pie in a 400 degree oven for about 20 minutes, then reduce the heat to 350 and bake for an additional 40 minutes until the pie is a nice golden brown. Let the pie set for several hours to set. If you can't wait that long, it will still taste great, but will probably not hold its shape very well.