Pour the sugar into the egg whites a little bit at a time while mixing.
When the mixture is thick and stiff (ie. You should be able to turn the bowl upside down without the mixture falling out), add the vanilla and vinegar.
Mix just enough to combine.
Line a cookie sheet with baking paper, and heat oven to 250 F.
Spoon the mixture into a circle, about 1 inch thick. Then build it up around the sides to create a bowl shape with a nice well in the center.
Bake for 1 hour, then turn the oven off and leave the shell inside for several hours. Do not open the door until it is fully cooled.
Keep the base in a cool, dry place for up to 2 days, until you’re ready to use it. It should be crisp on the outside and sticky and marshmallowy on the inside.
Filling Ingredients:
1.5 cups heavy cream (dairy) OR 8 oz. Rich’s Whip (non-dairy).