Preheat oven to 350°F Grease and flour a 12-cup Bundt pan (I use Pam Baking spray).
Add sugar and butter to a large mixing bowl. Beat on low until light and fluffy. Slowly add the eggs, one at a time, and continue mixing until well incorporated. Add the pumpkin, sour cream and vanilla, mixing on slow speed until well blended.
While mixer is still going on slow, add the flour, one cup at a time. Next, add the cinnamon, baking soda and salt. Blend until well incorporated.
Pour cake batter into prepared Bundt cake. Bake for 60 minutes or until a knife inserted into the center comes out clear.
For the glaze: Place powdered sugar in a medium bowl. Slowly whisk milk into the powdered sugar. Continue whisking until no lumps appear.
Continue whisking while adding vanilla, canned pumpkin, cinnamon and melted butter.
Once glaze is smooth, gently pour over the top of the Bundt cake, allowing to drizzle down the side of the cake.