Swirled Easter Cake with Vibrant Colors

Ingredients

• 1 box white cake mix
• 1/4 cup water
• 4 egg whites
• 1/2 cup vegetable oil
• 1 cup sour cream
• 1 tsp clear vanilla extract
• blue, pink, yellow food coloring
• pastel sprinkles or Easter candies
• 1/2 cup butter, softened
• 2 cups powdered sugar
• 1/4 tsp salt
• 1 1/2 tsp vanilla extract
• 2-4 tbsp heavy cream
• food coloring (optional)