1. Preheat oven to 350°F degrees.
2. Add cupcake liners to a cupcake/muffin pan. Set aside.
3. To a large bowl add dry ingredients: flour, sugar, baking powder and salt, whisk to combine. Set aside.
4. Add milk, vegetable oil, vanilla extract and eggs to a mixer bowl and whisk until fully combined, about 1 minute on medium speed.
5. Add the dry ingredients to the wet ingredients and beat until well combined. Stop once to scrape the sides and bottom of the bowl with a spatula.

6. Slowly, with the mixer on low speed, add the water and 10 drops of purple gel food color to the batter and mix just until combined. Scrape down the sides of the bowl as needed to make sure everything is well combined. If you want the color more intense, add more gel color, stir to combine, careful not to over-mix.

7. The batter is thin, I find it easier to add it to a pancake dispenser, this makes filling the cupcake liners much easier and mess free.
8. Fill the cupcake liners just a little over half.

9. Bake for 15-20 minutes, or until a toothpick comes out with a few moist crumbs NOT raw batter. In my oven, the cupcakes were perfectly done at the 20-minute mark. Do NOT open the oven until 15 minutes have passed. Start checking on the cupcakes at the 15-minute mark. If you are baking mini cupcakes, they may be done in 9-12 minutes, start checking after 9 minutes.

10. Remove the cupcakes from oven and allow to cool for 3-5 minutes in the pan, then remove to a cooling rack to finish cooling.

Frosting:

1. Add butter to a large mixer bowl and mix until smooth.
2. Add 4 cups of powdered sugar and mix until smooth.
3. Add the vanilla extract and milk, mix until smooth.

4. Add the remaining 4 cups of powdered sugar and mix until smooth. If the buttercream is too soft, add more sugar, 1/2 cup at a time.

5. Divide buttercream equally into 4 medium bowls.
6. Add a few drops of purple gel food color to one of the bowls, about 7-10 drops, and stir with a spatula to fully combine. Set aside.
7. Add a few drops of blue gel food color to one of the bowls, about 7-10 drops, and stir with a spatula to fully combine. Set aside.
8. Add a few drops of orange gel food color to one of the bowls, about 7-10 drops, and stir with a spatula to fully combine. Set aside.
9. Add a few drops of pink gel food color to one of the bowls, about 7-10 drops, and stir with a spatula to fully combine. Set aside.

Assembling:

1. Start by preparing your work area, gel food color can easily stain your working surface so cover it with parchment paper or plastic wrap.
2. Fix a piping bag with a large star tip, or any other piping tip that you like. Set aside.
3. Cut about 15 inches of plastic wrap and place it on the counter. In the middle of the plastic wrap add about 1/3 of the purple buttercream, spread it into a 6x6inches square.
4. Top it with 1/3 of the blue buttercream, and carefully, spread it on top of the purple square. Top it with 1/3 of the orange buttercream, and carefully, spread it on top of the blue layer.
5. Top it with 1/3 of the pink buttercream, and carefully, spread it on top of the orange layer.
6. Before adding the buttercream to the plastic wrap take a look at the piping bag you will be using, some are smaller and some are larger, so make sure the buttercream wrap once rolled is not larger than the piping bag, as it won't fit.
7. Roll the wrap, so it forms a tube, and place the wrapped buttercream inside the piping bag. Do a first, pipe and dump test, to get the buttercream closer to the tip.
8. Pipe the buttercream onto the cupcakes and decorate with edible glitter stars or sprinkles.
9. Repeat with the rest of the buttercream and cupcakes.
10. Refrigerate cupcakes at least one hour before serving.
11. Store in the refrigerator for 3-4 days.
12. Enjoy!