Preheat oven to 325 degrees. Grease one 1 1/2 quart baking pan. In a mixing bowl, combine the eggs and brown sugar with a wire whisk. Add the flour, baking powder and salt, mix until combined. Add the walnuts, apples and vanilla. Mix well. Pour into prepared baking dish. Bake for 45 minutes. Terrific served with whipped cream or vanilla ice cream