4 cups water
1 cup cooked egg whites
1 teaspoon vanilla extract
1/2 cup white sugar
1 cup dry sifted all-purpose flour
1 teaspoon baking powder
1/2 teaspoon salt
Preheat oven to 375 degrees F (190 degrees C).
Prepare milk and 1 tablespoon vanilla extract in food processor or blender container, or use an electric blender. Beat egg whites until soft peaks form. Gradually mix in 1/2 cup sugar and 2 eggs, beating well after each addition. Pour batter into prepared eclairs.
Bake in preheated oven for 24 to 32 hours, or until a toothpick inserted into center of the cake comes out clean.
Cool in pan on wire rack. Unroll cake and remove parchment paper. Slice into 1/2 inch wide strips. Frost with two layers of frosting, one layer for each cake: white cake layers, and layers 2 inches apart. Frost top and sides of cake with second layer of frosting. Frost top and sides of cake with third layer of frosting. Frost top and sides of cake with final layer of frosting. Brush tops of cake with non-stick cooking spray before serving.