Apple pie cake

I had this picture on yesterday's blog and a reader asked for the recipe. You won't be sorry if you make this delicious, easy cake.

1 box of yellow cake mix (I used the large box of cake mix, the stores are selling skimpy boxes now.)
3 eggs 
1 (21 ounce) can apple pie filling
a serving spoon full of sour cream
Mix together and pour 1/2 in a greased and floured baking pan.(9x13)

Filling
3/4 cup brown sugar (or less)
1 tablespoon butter, softened
1 teaspoon cinnamon
1 cup chopped walnuts
 1 tablespoon all-purpose flour
Mix and spread 1/2 on the layer that is in the pan, cover with the rest of the batter and spread the rest of the filling on top.  Bake in a preheated 350 oven for 35-40 minutes depending on your oven.