Preheat oven to 350°F degrees.
Add cupcake liners to a cupcake/muffin pan. Set aside.
To a large bowl add dry ingredients: flour, sugar, baking powder and salt, whisk to combine. Set aside.
Add milk, vegetable oil, vanilla extract and eggs to a mixer bowl and whisk until fully combined, about 1 minute on medium speed.
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.
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.
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.
Fill the cupcake liners just a little over half.
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.
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.