Blue Velvet Cake

INGREDIENTS

for the cake:

1 box white cake mix

3 egg whites

1/3 cup oil

1-1/4 cup buttermilk

2 tbsp cocoa powder (not dutch)

2 tsp blue food coloring gel

few drops violet food coloring gel

for the frosting:

8 ounces cream cheese, cool

1/2 cup butter, room temperature

3 cups powdered sugar

1 tsp pure vanilla extract

dash salt