Funfetti Sheet Cake

I remember being in elementary school and feeling like we hit the jackpot every time someone brought in funfetti cupcakes. They were the best! And remember the rainbow chip frosting...I hate that stuff out of the jar in middle school and high school.  That's also when I weighed maybe 110lbs....pretty sure if I looked at that jar now I would gain 5lbs.   Anyways, when I saw this recipe I new I had to find a fun occasion to make it.  I was originally going to make it for a friend's birthday but then our plans got canceled because of snow so I held off and made it a few weeks later when we got together next.  Everyone raved about it.  This recipe is from Eat Cake For Dinner.

Cake:
1 cup unsalted butter
1 cup water
2 1/4 cups all-purpose flour
2 cups sugar
1/2 tsp salt
1 tsp baking soda
1/2 cup sour cream
2 eggs
1 tsp vanilla
6 tbsp sprinkles (and more for garnish)

Icing:
1 cup unsalted butter
6 tbsp evaporated milk
4 1/2 cups powdered sugar
pinch of salt
2 tsp vanilla

Heat oven to 375.  In a small pan combine the water and butter, stir until the water has melted.  In a medium mixing bowl combine the flour, sugar, salt and baking soda.  Stir in the butter mixture. Whisk in the eggs, sour cream and vanilla.  Fold in the sprinkles.  Pour into a greased 12x17 sheet pan.  Bake for 20 to 24 minutes or until the cake is cooked through.  Remove from oven and let cool for at least 45 minutes before making the icing.  Once the cake is cooled place the powered sugar in a medium mixing bowl.  In a saucepan combine the butter and evaporated milk.  When the butter is melted whisk it into the powdered sugar until smooth.  Add the sat and vanilla while whisking.  Pour over the cake and let set for 5 minutes before topping with sprinkles.