Topping:
1/4 cup flour
2 tablespoons sugar
1/4 teaspoon cinnamon
2 tablespoons chilled butter
1/3 cup finely chopped walnuts
Cake:
2 cups flour
1 cup sugar
3 teaspoons baking powder
1/2 teaspoon baking soda
1 teaspoon salt
1 1/2 teaspoons cinnamon
1/2 teaspoon allspice
1/4 cup butter, melted
1 cup sour cream
2 eggs
1 1/2 cups apples, peeled, cored and diced
Topping:
Mix flour, sugar and cinnamon together. Cut in butter until crumbly. Stir in walnuts. Set aside.
Cake:
In a large bowl, mix flour, sugar, baking powder, baking soda, salt, cinnamon and allspice. In a small bowl, whisk together the melted butter, sour cream and eggs. Pour all at once into the dry mixture and beat until the batter is smooth. Stir in apple. Spoon batter in a greased 9 inch tube cake pan. Sprinkle the topping mixture over. Bake at 350 degrees F. for 45 to 55 minutes. Cool in pan for 20 minutes. Run a knife around the cake to loosen, and remove from pan.