Preheat the oven to 350°F (175°C) and grease a 9x13 inch baking pan.
In a large mixing bowl, combine the yellow cake mix, instant lemon pudding, oil, eggs, water, vanilla, and lemon zest. Mix until well combined.
Pour the batter into the prepared baking pan and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
While the cake is baking, prepare the glaze by mixing powdered sugar, melted butter, heavy whipping cream, lemon juice, and lemon zest in a small bowl.
Once the cake is done, remove it from the oven and let it cool slightly. Drizzle the glaze over the warm cake.
Allow the cake to cool completely before serving. Enjoy!