Preheat oven to 350 degrees. Grease and flour a 9 x 13 inch pan. Cream butter and sugar; add eggs, sour cream and vanilla. Sift together flour, baking powder and salt; add to the creamed mixture and blend. Pour half of the batter into the baking pan.
Mix together 1 cup nuts, brown sugar and cinnamon and sprinkle onto the batter in the pan; cover with remaining batter. Top with remaining nuts. Bake 60 minutes. Serves 10 to 12. (Great for morning coffee or a Christmas breakfast.)