Preheat oven to 350° F.
Grease and flour 12-cup bundt pan.
Mix 1/4 cup of sugar and cinnamon in a small bowl. Set aside.
In medium sized bowl, whisk together flour, baking powder and baking soda.
In large bowl, combine sugar, eggs and vanilla, beat well.
Add melted butter or margarine. Beat well.
Beat in butter milk.
Add blended flour into creamed mixture.
Beat until smooth.
Blend in chopped walnuts.
Pour one half batter into greased and floured bundt pan.
Sprinkle the mixture of sugar and cinnamon over batter.
Top with remaining batter.
Insert flat utensil part-way into batter and turn through batter twice. Do not touch the bottom or sides of pan with utensil.
Bake at 350 degrees F for 60 minutes or until cake tests done.