Preheat oven to 350F.
Line a muffin tray with cupcake liners and set aside.
In a large bowl, beat together the white cake mix and Sunkist for a total of 2 minutes.
Scoop the batter with a measuring cup into the cupcake liners.
Bake for 25-30 minutes, until an inserted toothpick comes out clean
Allow the cupcakes to cool completely before frosting.
Place 1 cup of Sunkist in a saucepan and heat until boiling over medium-high heat.
Reduce to medium-low and simmer until reduce to 1/4 (2 oz of soda should remain). Allow to cool completely.
In a large bowl, beat together the butter and powdered icing sugar for 2-3 minutes, then add the reduced Sunkist soda.
Beat to mix well together, then add the milk as needed to receive a spreadable texture. Adjust the color with orange food dye, if needed.
Use an angled spatula to spread 1-2 Tablespoons of frosting onto each cooled cupcake.
Put the sugar crystals in a small bowl and roll the cupcakes in the sugar crystals to cover completely.
Scoop the rest of the frosting into a piping bag and snip off the bottom 1” of the piping bag.
Swirl a 1” circle onto each cupcake and garnish with orange sprinkles.