Apple Coffee Cake With Brown Sugar Sauce

1. 2 apples - peeled, cored and chopped
2. 2 1/2 cups all-purpose flour
3. 1 1/2 cups packed brown sugar
4. 3/4 cup butter, softened
5. 1 cup chopped walnuts, toasted
6. 1 teaspoon baking soda
7. 1 teaspoon ground cinnamon
8. 1/2 teaspoon salt
9. 1 egg
10. 3/4 cup sour cream
11. 1 teaspoon vanilla extract
1. Preheat oven to 375 degrees F (190 degrees C). Butter a 9 inch round cake pan or 9 1/2 inch springform pan.
2. Using a fork, work flour with brown sugar and butter in a large bowl until crumbly. Stir in nuts. Divide mixture in half. Evenly press half into pan bottom to form a crust.Stir baking soda, cinnamon, and salt into remaining crumb mixture until blended, then make a well in the center. In a small bowl, lightly beat egg with sour cream and vanilla until smooth. Add to flour mixture, stirring just until combined. Fold in apples.Evenly spread batter over crumb mixture. Bake until a cake tester inserted into center comes out fairly clean, about 1 hour and 20 minutes. If top gets too brown before cake is baked, lightly lay a piece of foil over top for last 10 to 20 minutes of baking. Cool in pan on a rack. Serve with Brown Sugar Sauce. Cake keeps well at room temperature for a day. Covered, it freezes well and is easily cut while still frozen. 
1. I had to look up the brown sugar sauce on allrecipes, but it was easy to find. The crust was pretty hard to cut through. Maybe if I would have remembered to add the nuts into the crust part it wouldn't have been so hard. We had it for family night treat, breakfast, a quick afternoon pick me up, a late night snack.