Adjust the oven rack to the center of the oven and preheat to 350°F. Line 24 standard muffin cups with paper liners and set aside.
In a bowl, mix together the flour, baking powder, baking soda, and salt.
In the bowl of an electric mixer fitted with the paddle attachment, beat together the sugar, pink lemonade concentrate, oil, and egg whites until well blended. Add half the dry ingredients and mix until just combined. Then add the buttermilk and mix again, followed finally by the remaining dry ingredients. Do not over mix. Add red food coloring one drop at a time to achieve desired pink color. The color will fade slightly when baked.
Fill each liner ¾ full with batter. Bake the cupcakes for about 18 minutes or until a toothpick inserted into the center comes out clean. Cool cupcakes completely.
To make the frosting, in the bowl of an electric mixer fitted with the paddle attachment beat the butter until nice and fluffy. Pause the mixer occasionally to add the confectioners’ sugar ½ cup at a time and beat until combined and fluffy. Add the pink lemonade concentrate, lemon juice, and a pinch of salt and beat until smooth and fluffy. Add red food coloring one drop at a time to achieve desired pink color.
Fill a pastry bag fitted with a large piping tip (preferably a closed star tip to achieve a rose look) with the frosting and frost the cupcakes as desired. To achieve a rose look with the frosting, pipe in a circle from the center of the cupcake outward.
Frosted cupcakes can be refrigerated up to 2 days in airtight containers; bring to room temperature before serving.
If you can find frozen pink lemonade concentrate that is devoid of corn syrup, I recommend you use it. I believe most of them feature corn syrup of some kind, but the concentrate really is the most impactful way to cram all that lemonade flavor in there. If you’d like, you can easily use this Frozen Organic Lemonade Concentrate from Cascadian Farms or Trader Joe’s Frozen Lemonade Stand Lemonade. These are for regular lemonade, not pink lemonade, but don’t contain any corn syrup and will make very little difference in the final result (color-wise) since you’ll be adding food coloring anyway. They can be found at Whole Foods and Trader Joe’s respectively. If you’re concerned about the corn syrup factor, then definitely go this route.