Lemon Banana Cloud

4 egg whites
1/2 cup granulated sugar
3 very ripe bananas, mashed
Grated rind of 1 lemon
1 teaspoon vanilla extract

Beat egg whites until stiff. Still beating, slowly add sugar, banana pulp, lemon rind and vanilla extract. Pour gently into a buttered casserole. Bake at 350 degrees F until set and brown, about 25 to 30 minutes. Serve cold. This is better if made the day before serving.