Ingredients:
1 cup walnuts, toasted
1/2 cup brown sugar, packed
2 tablespoons all-purpose flour
1 teaspoon cinnamon
2 tablespoons unsalted butter, cut into bits
3 cups granny smith apples, peeled and chopped into 1 x 1 inch pieces ( approx)
1 tablespoon sugar
1 teaspoon cinnamon
1 teaspoon lemon juice
3/4 cup sour cream
1/4 cup buttermilk or 1/4 cup milk
2 3/4 cups all-purpose flour
1 teaspoon baking powder
1 teaspoon baking soda
3/4 teaspoon salt
1 cup butter, room temperature
1 cup sugar
3/4 cup brown sugar, packed
3 large eggs
1 teaspoon lemon juice
2 teaspoons vanilla extract
Directions:
For Topping: Blend walnuts, brown sugar, flour, cinnamon in processor until nuts are finely chopped.
Add butter and cut in using on/off turns until clumps begin to form.
(Can be made 1 day ahead) Cover and chill.
For Filling: Mix apples, sugar, cinnamon, and lemon juice in a bowl.
For Cake: Preheat oven to 350F.
Butter 13 x 9 x 2 inch glass baking dish.
In a small bowl, whisk sour cream and buttermilk to blend.
In a medium bowl, sift flour, baking powder, baking soda, and salt.
In a large bowl, beat butter and both sugars until creamy.
Add eggs, one at a time, beating well after each addition.
Mix in lemon juice and vanilla extract.
Beat in dry ingredients alternately with sour cream mixture in 3 additions each, mixing just until smooth.
Spread half of batter in prepared pan.
Spoon apple filling on top of batter.
Spread remaining batter over filling.
Sprinkle with topping.
Bake cake until tester inserted into center comes out clean, about 45 minutes.
If the top starts browning too quickly, cover with foil.
Servings: 15
Time preparation: 25 min.
Time total: 70 min.