==Topping==

  * 1/3 cup light brown sugar
  * 1/2 cup granulated sugar
  * 1/2 cup chopped walnuts
  * 1 tsp ground cinnamon

  - In a bowl, combine sugars.
  - Mix in the cinnamon and walnuts.

==Cake==

  * 2 cups flour
  * 1 tsp baking powder
  * 1/2 tsp baking soda
  * pinch salt
  * 1 cup butter at room temperature
  * 1 1/4 cups granulated sugar
  * 2 eggs
  * 1 tsp vanilla
  * 1 cup sour cream
  * 2 large apples, peeled and sliced

===Method==
  - Oven to 350. Butter a 13x9 pan.
  - Stir together flour, baking powder, baking soda and salt.
  - In an electric mixer, cream butter and sugar until fluffy; Add eggs and vanilla.
  - On lowest setting, alternate beating flour mix and sour cream into batter.
  - Spread half the batter in the pan. Sprinkle with topping. Cover with apple. Sprinkle with topping. Spread remaining batter on top; finish with topping.
  - Bake for 40 minutes, until a toothpick in the center comes out clean.
  - Cool on a rack for 30 minutes.

===Tags=== 
Boston Globe, by Sarah Hearn