In a medium bowl, mix flour, baking soda and salt. Set aside.
In a large bowl/stand mixer, cream butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in vanilla, pumpkin and vegetable oil. Beat in the flour mixture alternately with the milk.
Divide batter evenly into prepared pans. Bake for 35-40 minutes, or until a toothpick inserted into the center of the cake comes out clean. Remove pans from oven and immediately place in freezer for 45 minutes. (This keeps the cake moist by immediately stopping the baking so the cake does not continue to bake when you remove it form the oven.)
For the frosting: In a large bowl, cream butter and cream cheese until smooth. Beat in maple syrup, vanilla and cinnamon. Add confectioners’ sugar and beat on low speed until combined, then on high until frosting is smooth.
Assemble the 3 layers with a thick layer of frosting in between each layer. Then apply a thin crumb coat on the top and sides. Pop back in the freezer to harden the crumb coat for about 10 minutes.
Apply one final thick and even layer around the outside of the cake. Store in the fridge until ready to serve.