Preheat oven to 325 degrees. Spray a 9-inch pie pan with non-stick spray.
Beat egg whites and baking powder until stiff peaks form. Blend in sugar and vanilla to complete the meringue.
Crush crackers with a rolling pin on a silpat or waxed paper. Or place into a plastic bag and pound. Mix with chopped nuts. Fold cracker mixture carefully into the meringue, taking care to deflate as little as possible.
Pour into the prepared pie pan.
Bake for 30 minutes at 325 degrees until pie loses its gloss and is dry on top. Cool completely.
To serve, cut into pieces and top with whipped cream and garnish of your choice.
I am not a health professional and nutrition data is calculated programatically. Accuracy may vary with product selection, calculator accuracy, etc. Consult a professional for the best information.