1/2 cup chopped walnuts
2 teaspoons ground cinnamon
1 1/2 cups sugar, divided
1/2 cup butter or margarine, softened
2 eggs
1 teaspoon vanilla extract
2 cups all-purpose flour
1 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1 cup sour cream
1 medium apple - peeled, cored and thinly sliced

Combine nuts, cinnamon and 1/2 cup sugar; set aside. In a large mixing bowl, cream butter; gradually add remaining sugar, beating until light and fluffy. Add eggs, one at a time, beating well after each addition. Blend in vanilla. Combine dry ingredients; add to creamed mixture alternately with sour cream, beating well after each addition. Spread half of the batter in a well greased 10-in. tube pan with a removable bottom. Top with apple slices; sprinkle with half of the nut mixture. To with remaining batter, then with remaining nut mixture. Bake at 375 degrees F for 40 minutes or until cake tests done. Remove from oven; let stand 30 minutes. Loosen sides of cake; lift cake with removable bottom from pan. Cool. Before serving, carefully lift cake from pan.

Source: allrecipes.com