Preheat the oven to 325°F. Grease and flour a 10" bundt or tube pan. 

In a large bowl, mix together the butter, shortening, and sugar until light and fluffly. Beat the eggs into the mixture one at a time, only mixing until the yellow disappears. 

In a medium bowl, combine the flour, baking powder, and cinnamon. 

Stir the dry ingredients into the butter mixture, alternating with the mik. Make sure it is mixed well. Add the vanilla and walnuts. 

Pour batter into your pan.

Bake for 1 hour and 30 minutes or until a toothpick inserted into the crown of the cake comes out clean. 

Cool inside the pan for 15 minutes before flipping the cake onto a wire rack and removing the pan. Cool completely before serving.