Preheat oven to directions on back of cake mix packaging. Mix the eggs, oil, 1 Cup water and cake mix until smooth on medium speed about 2 minutes with hand mixer.
Divide the cake batter into 5 separate bowls. It makes about 5 perfect cups of batter. Using food coloring, color each bowl according to the colors of the Zours. I kept each one of the Zours out to try and match the color as close as I could.
Each color makes 3 cupcakes, with a touch of each batter left over. Bake according to directions on back of cake mix box. Let cool on wired rack completely.
While cakes are cooking and cooling, make the frosting. Cream the butter and slowly add in the powdered sugar until combined. Add in the vanilla and 1 1/2 Tbls milk/water and whip on medium speed for 3 minutes until light and fluffy with hand mixer. If mix is a little thicker than you would like, add remaining 1/2 Tbls of liquid. Mix again until fully incorporated.
Frost cupcakes and garnish with Zours of the same color. Serve and enjoy!