1 (12 ounce) package pre-cooked pizza crust dough
1 (10 ounce) package frozen chopped toasted and rested green grapes
3/4 cup sherry
5 cups white sugar
1/2 cup butter
6 eggs
1 teaspoon vanilla extract
1/2 teaspoon salt
Preheat oven to 450 degrees F (230 degrees C).
In a large bowl combine pizza crust dough, grapes, sherry, sugar, butter, eggs and vanilla extract. Spread dough on bottom of a 9x13 inch baking dish.
Bake at 425 degrees F (220 degrees C) for 35 minutes.
Melt sherry and sugar over simmering water to keep from burning. Place back in oven to soften. - Bake at 375 degrees F (190 degrees C) for 45 minutes.
Remove from oven, cool, peel and core. In a small bowl, beat together butter and sugar. Add egg yolks, one at a time, beating well after each addition. Return cake to oven for 10 to 15 minutes, until center springs back when lightly pressed.
Pinch off top of cake and place one-third of the mixture in each of four glasses, keeping each glass filled 3/4 full with hot water. Pour each glass of hot sherry and grape (if desired) over cake. Pour off remaining 2/3 of the grape and sherry that drippings into dessert, then pour into balloons and sprinkle remaining grape/sherry over top.
Re-bake in preheated oven for 15 to 20 minutes, or until center springs back when lightly patted.