Apple Sour Cream Coffee Cake

Step 1

For Topping: Blend walnuts, brown sugar, flour, cinnamon in processor until nuts are finely chopped.

Step 2

Add butter and cut in using on/off turns until clumps begin to form.

Step 3

(Can be made 1 day ahead) Cover and chill.

Step 4

For Filling: Mix apples, sugar, cinnamon, and lemon juice in a bowl.

Step 5

For Cake: Preheat oven to 350F.

Step 6

Butter 13 x 9 x 2 inch glass baking dish.

Step 7

In a small bowl, whisk sour cream and buttermilk to blend.

Step 8

In a medium bowl, sift flour, baking powder, baking soda, and salt.

Step 9

In a large bowl, beat butter and both sugars until creamy.

Step 10

Add eggs, one at a time, beating well after each addition.

Step 11

Mix in lemon juice and vanilla extract.

Step 12

Beat in dry ingredients alternately with sour cream mixture in 3 additions each, mixing just until smooth.

Step 13

Spread half of batter in prepared pan.

Step 14

Spoon apple filling on top of batter.

Step 15

Spread remaining batter over filling.

Step 16

Sprinkle with topping.

Step 17

Bake cake until tester inserted into center comes out clean, about 45 minutes.

Step 18

If the top starts browning too quickly, cover with foil.