Preheat your oven to 350 degrees F and generously spray your bundt pan with non-stick spray. Set aside.
In a large bowl, add the cake mix, dry pudding mix, milk, melted butter, and eggs. Beat on low for 30 seconds then medium for 2 minutes. The batter will be thick & fluffy (thanks to the pudding!)
Spoon evenly into the prepared pan and bake for 30-35 minutes or until a toothpick inserted into the center comes out clean.
Remove from the oven and let cool for about an hour. Flip over onto a plate.
For the Powdered Sugar Glaze:
While the cake is cooling, to a medium bowl, add the powdered sugar, melted butter, water, and vanilla. Whisk together until smooth.
Once the cake has cooled, pour the glaze over the cake.