https://therecipecritic.com/2017/02/best-red-velvet-cupcakes-cream-cheese-frosting/
Preheat oven to 350 degrees. Line a muffin tin with paper liners and spray with cooking spray; set aside. In the bowl of a stand mixer, combine butter and sugar and mix on medium speed until very light and fluffy, about 5 minutes. Add the eggs, one at a time, beating well after each addition. In a small bowl, whisk the food coloring, cocoa powder and vanilla together; add to the butter/sugar mixture and mix well. Stir the salt into the buttermilk and add to the batter in three parts, alternating with the cake flour, starting and ending with flour. In a small bowl, stir together the vinegar and baking soda; add to the batter and mix well.
Fill cupcake liners ⅔ full with batter and bake in preheated oven for 17-18 minutes or until a toothpick inserted in the center comes out clean. Do not over bake. Repeat with remaining cupcakes. Cool completely and top with Cream Cheese Frosting. Makes about 3½ dozen cupcakes.
For the Cream Cheese Frosting: In a large bowl, mix together butter, cream cheese, salt and vanilla until smooth. Add powdered sugar, one cup at a time, beating well after each addition. If frosting is too thick, add a little milk. If you are planning to pipe the frosting onto the cupcakes, you want it thick enough to hold its shape. This makes enough frosting to pipe a big swirl on the top of each cupcake. I used a Wilton 1M piping tip.
*If you do not want to pipe a large swirl onto each cupcake and prefer to spread a small layer on top instead, the amount of frosting can be cut in half.