• 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 and salt. Whisk together.
• Add your butter and water 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 cake batter into the prepared pan.
• Bake the cake for 18-23 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 milk 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 and vanilla extract to a 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.