Begin by preheating your oven to 350 degrees F. Then grease and flour a 15x10x1-inch baking pan. Set aside.
In a medium bowl, whisk together the flour, baking soda, baking powder, cinnamon, pumpkin pie spice, nutmeg, and cloves. Set aside.
In a stand mixer (or large bowl with hand mixer), beat the butter for about one minute. Then beat in the sugar until light and fluffy (about two more minutes). Add eggs, pumpkin, sour cream, milk and vanilla; beat until combined. (It's OK if your batter looks curdled or separated.) Add in your flour mixture and beat until just combined.
Spread the mixture evenly into your prepared baking pan. Bake for 25 to 30 minutes or until a toothpick inserted near the center comes out clean. Cool on wire rack.
For the frosting, combine cream cheese, butter, salt and vanilla. Beat with an electric mixer until light and fluffy. Slowly beat in the powdered sugar, one cup at a time. Continue beating until the frosting is smooth.