Preheat oven to 400F. Peel squash, cut tip (like for potato salad) and boil until tender. Drain, then mash. Add sugar and mix well. Add egg, flour, baking powder, and vanilla in that order. Pour in pan sprayed with Pam. Bake about 20 minutes or until set in middle.
Add cream of tartar and vanilla to egg whites and beat until soft peaks form. Gradually add sugar until stiff peaks form. Layer on top of pudding and bake until lightly browned.
Cajun Country -- New Iberia, Louisiana