In a large mixing bowl, whisk together the cinnamon, sugar, eggs, butter, flour and water until blended well.
Pour into the pie crust, than place the pie crust on top of a baking sheet before placing in the oven.
Bake at 375 degrees for 45-50 minutes or until pie is set. If pie hasn't set, cover with a piece of aluminum foil and allow to bake for 10-15 minutes longer to prevent the crust and top from burning.
Remove from oven and allow to cool for several hours to allow pie to set firmly. Serve with whipped cream or vanilla ice cream if desired.
Notes
Store leftover pie in the refrigerator for several days.