1Preheat oven to 325°F; grease a 12-cup Bundt pan or a 10x4-inch tube pan.
2Prepare apple-nut filling: Cook all ingredients, except nuts, over medium heat, stirring constantly. Cook until apples are tender. This will take approximately 3 to 4 minutes. Stir in nuts. Set aside.
3Combine sugar, butter, vanilla and eggs in a large mixing bowl. Beat at medium speed, 2 minutes, scraping bowl occasionally.
4Alternately add the dry ingredients and the sour cream, beginning and ending with the dry ingredients. Beat well between each addition on low speed.
5Spread 1/3 of the batter (about 2 cups) in the baking pan. Top with 1/3 of the filling. Repeat this pattern 2 more times, until all batter and filling have been used.
6Bake at 325°F for 1 hour, until a toothpick inserted near the center comes out clean. Cool in the pan for 20 minutes, then turnout onto a serving plate and cool completely.