Vanilla Coconut Texas Sheet Cake

1 cup butter
1 cup water
2 cups flour
2 cups sugar
2 eggs
1/2 cup sour cream
2 teaspoons vanilla extract
1 teaspoon salt
1 teaspoon baking soda
1/2 cup coconut, optional

1/2 cup butter
1/4 cup milk
4 1/2 cups powdered sugar (or less if you don't like frosting to be too sweet)
1 1/2 teaspoons vanilla extract
Toasted coconut, optional

How to make it

Preheat oven to 350 degrees F. Line a 9 x 13 pan with foil and lightly spray with nonstick cooking spray.
In a large saucepan, bring the butter and water to a boil. Remove from the heat and stir in the sugar, eggs, sour cream and vanilla extract. Add the flour, salt and baking soda; stir until just combined.
Pour into prepared pan. Bake for 25-28 minutes or until toothpick inserted in the center comes out clean and top springs back when lightly pressed.
To make the frosting: in a medium saucepan, bring butter and milk to a boil. Remove from heat and add the powdered sugar and vanilla extract. Mix until smooth. Pour over warm cake and garnish with toasted coconut.