01 -
Heat your oven to 350°F and lightly grease a 9x13 baking dish. Set it aside while you prepare the batter.
02 -
In a large bowl, beat together the cake mix, water, egg whites, oil, sour cream, and vanilla extract using an electric mixer. Mix on low for about 30 seconds until combined, then scrape down the sides. Beat on medium speed for another 2 minutes, occasionally scraping the bowl.
03 -
Pour about 2 cups of the white batter into your prepared pan. Divide the remaining batter between 3 medium bowls (roughly ½ cup each). Add a few drops of food coloring to each bowl - blue in one, pink in another, and yellow in the third. Stir each until you reach your desired color intensity.
04 -
Drop spoonfuls of each colored batter randomly over the white batter in the pan. Use a butter knife to gently swirl the colors through the white batter, creating a beautiful marbled effect.
05 -
Bake in your preheated oven for 30-35 minutes. The cake is done when a toothpick inserted in the center comes out clean. Allow the cake to cool completely before frosting.
06 -
In a mixing bowl, whip the softened butter for 1-2 minutes until light and fluffy. Add powdered sugar and salt, then beat on low to medium speed for about a minute, scraping the bowl occasionally. Mix in the vanilla extract and 2 tablespoons of cream. Add more cream as needed until you reach your desired consistency, then whip for another minute until light and fluffy.
07 -
Once the cake has cooled completely, spread the vanilla frosting evenly over the top. Decorate with colorful Easter sprinkles for a festive touch.