Use butter or a neutral cooking spray to grease 2 9 pie pans or 1 9x13 inch pan.
In a small bowl combine melted butter, crushed graham crackers, and sugar. Stir until the crumbs start to adhere together. Add the water, a Tablespoon at a time, until the crust sticks together if pinched between two fingers. Divide the mixture evenly between the two pie pans, using your fingers or the bottom of a measuring cup to press it into the bottoms and up the sides of the pan. Place the crusts in the freezer while you prepare the filling.
In the bowl of an electric mixer fitted with the whisk attachment, beat the eggs whites on high speed for 1 minute, or until frothy. Add the frozen strawberries and granulated sugar in three separate additions, beating well after each addition. Continue to whisk the mixture until light, fluffy, and tripled in size. Gently stir in Cool Whip and vanilla.
Divide the mixture evenly between the two pie crusts, smoothing the top. Flash freeze for 1 hour, then wrap tightly with saran wrap and freeze for at least 8 hours or overnight. To serve, place the frozen pie in about an inch of very hot water for 30-60 seconds. Slice and serve immediately with fresh strawberry slices, whipped cream, and chocolate, if desired.