• Preheat the oven to 375 degrees Fahrenheit.
• Spray a jelly roll pan (15x10inches) with nonstick spray.
• In a large bowl combine the flour, sugar, baking soda, salt, and lemon zest. Whisk together.
• Add your butter, water, and lemon juice to a sauce pan and bring to a boil over medium high heat.
• Remove from heat and pour into the flour mixture. Stir until combined.
• Add in the eggs, sour cream, and vanilla extract and stir it all together.
• Pour the cake batter into the prepared pan.
• Bake the cake for 15-25 minutes, or until a toothpick inserted in the center comes out clean (a few crumbs are okay).
• Cool the pan for 20 minutes.

For the Frosting:

• Add your butter and lemon juice to a medium sauce pan and cook over low heat until the butter melts.
• Raise temperature to a medium heat and bring to a boil.
• Add the powdered sugar to a medium sized bowl.
• Pour the melted butter mixture over the powdered sugar, and whisk together till nice and smooth.
• Pour frosting over the warm cake.
• Allow to cool completely before slicing and serving.