Preheat oven to 350 degree F. Generously grease and flour a 13x9x2-inch baking pan; set aside. In a medium mixing bowl combine gingersnaps, wheat germ, and brown sugar; cut in butter until crumbly. Stir in walnuts; set aside.
In a large mixing bowl combine cake mix and yeast. Add apple butter, water, and eggs; beat with an electric mixer on low speed until well combined. Beat 2 minutes on high speed. Spread in prepared pan; sprinkle with gingersnap mixture. Bake about 30 minutes or until a wooden pick inserted off-center comes out clean. Cool slightly. (Some areas of cake will drip slightly.) Meanwhile, in a small saucepan combine white baking pieces and butter; heat and stir just until melted. Remove from heat. Stir in powdered sugar and enough apple juice to make of drizzling consistency. Drizzle over coffee cake. Cool at least 1 hour on wire rack. Serve warm or at room temperature. Makes 12 servings.