Preheat oven to 350 degrees F.
Make the crust: Mix all crust ingredients together in a small bowl. While mixture is still warm from the butter, press it evenly into the bottom of a deep-dish pie pan. Bake for about 5 minutes, or until browned. Remove piecrust from oven.
Preheat oven to 425 degrees F.
Make the filling: Place all filling ingredients in a medium bowl and mix well with a wire whisk. Pour filling into prebaked piecrust. Bake for 15 minutes and then reduce the oven temperature to 350 degrees F. Continue to bake for an additional 50 to 55 minutes. To test for doneness, stick a toothpick in the center; if it comes out clean, the pie is done.
Cool and then chill before serving. To serve, top each slice with a dollop of low carb whipped cream.
With an electric mixer on high, whip the heavy cream just until frothy. Then add in the sugar substitute and vanilla extract and continue to whip on high until peaks form. Be careful not to over-whip, or cream will break. Transfer to a pastry bag or just spoon onto pie.