Scrumptious Coffee Cake

1/2 c butter
1 c sugar
2 eggs
1/2 tsp salt
1 tsp vanilla
2 c flour
1 tsp baking pwd
1 tsp baking soda
1 c buttermilk

Topping
1/2 c brown sugar
1/4 c white sugar
1 tsp cinnamon
2 tbsp flour
2 1/2 tbsp melted butter
1/2 c chopped walnuts

Mix buttter and sugar. Add eggs and vanilla well. Sift together flour, salt, baking pwd and soda. Add this alternately with buttermilk to the egg mixture. Pour half of batter into a greased 9 x 13 pan. Sprinkle some of the topping . Add remaining batter and top with remaining topping. Pat crumbs lightly into cake mixture. Bake at 350 degrees for 35 to 40 min.