Preheat the oven to 350 degrees. Spray a bundt pan with cooking spray really well, then dust with flour.
With a hand mixer, combine the cake mix, pudding, eggs, sour cream, water, a little lemon zest, and oil in a large bowl.
Spoon into the bundt pan and bake for 45-55 minutes. My oven bakes really slow, so mine always takes longer, but start checking around 45 minutes, just to make sure. Cake is done when a toothpick comes out clean.
Cool for 10-15 minutes, then turn out onto a cake plate. While it's cooling, make the frosting!
To make the frosting: Measure the powdered sugar into a large mixing bowl. Add the softened butter and a little bit of milk, beating until well combined, and adding a little milk as needed. When it's the right consistency, mix in the lemon extract and salt. I like to stir in a little lemon zest too!
After the cake has cooled, turn it out onto a cake plate. Microwave the frosting for about 20 seconds, until you can pour It over the cake In ribbons. Sprinkle lemon zest over the top.
Frosting Note: Instead of making a glaze, I like my frosting to be thicker. To make it easy to pour over the cake, I microwave it before pouring over the cake. Then as it cools, it hardens to be the consistency of buttercream frosting.