Dissolve yeast in warm water.
Sift together flour, sugar and salt.
Cut butter into flour mixture with 2 knives. (Don't have the butter too soft.)
Combine dissolved yeast, beaten egg and vanilla.
Stir into flour mixture, blending until smooth.
Place dough on a well floured board and roll into 10 by 14 inch rectangle.
Transfer dough to greased 11 x 7 x 2 inch baking pan, allowing extra dough to hang over sides of pan.
Spread fruit filling evenly over dough.
Fold overhanging dough back over fruit.
For crisp topping sprinkle 1/2 cup sugar on top of dough.
Bake in moderate oven 375° for 30 minutes.
Reduce heat to 300° and bake for 15 to 20 minutes longer, or until lightly browned.
Use any kind of fruit filling you prefer.