I don't know where Rob got this recipe. It's popular at IBOP.
Ingredients
1¼ cup white flour
3 Tbsp sugar
1 tsp pumpkin pie spice
2 tsp baking powder
½ tsp salt
¾ cup pumpkin or sweet potato
1⅓ cup milk
¼ cup butter
4 eggs, separated
1 tsp vanilla
Directions
Mix the dry ingredients. Mix the pumpkin, milk, egg yolks, butter and vanilla; pour them into the dry ingredients and mix.
Beat the egg whites, and fold them into the rest.