Preheat oven to 350°F. Lightly grease 9x13-inch baking dish. Combine first 3 ingredients in medium bowl and mix until finely crumbled. Stir in nuts. Press 2 cups of mixture evenly into bottom of prepared dish. Add cinnamon, baking soda and salt to remaining mixture and blend well. Beat in egg, sour cream and vanilla. Gently stir in apples. Spoon evenly into dish. Bake until cake begins to pull away from sides of dish and tester inserted in center comes out clean, about 35 to 40 minutes. Let cool completely in pan. Cut into squares. Top with vanilla ice cream. Makes about 24 squares dess 1