Smyth Estate Sweet Potato Apple Bake

Description
This recipe came from an estate sale. I obtained it when I purchased the family collection from the Smyth Estate in Plano, Texas in 1990.
 * Contributed by Catsrecipes Y-Group

Ingredients

 * 1 large cooking apple peeled and quartered
 * 2 cups mashed sweet potatoes
 * 2 eggs separated
 * ½ teaspoon vanilla extract
 * vegetable cooking spray
 * 1½ teaspoons butter
 * apple slices for garnish
 * lemon juice

Directions

 * 1) Place apple quarters in a saucepan then cover with water and bring to a boil.
 * 2) Reduce heat and simmer 8 minutes then drain well.
 * 3) Position knife blade in food processor bowl then add apples and process until smooth.
 * 4) Combine apples, sweet potatoes, egg yolks and vanilla then stir well and set aside.
 * 5) Beat egg whites at room temperature until peaks are stiff but not dry.
 * 6) Fold into potato mixture.
 * 7) Pour mixture into casserole dish coated with butter.
 * 8) Bake at 350°F for 45 minutes.
 * 9) Garnish with apple slices which have been dipped in lemon juice.