This is the recipe I used this weekend. My 11 year old (today) requested this for her birthday cake.
3 1/3 cups cake flour (NOT unbleached all-purpose flour). You have to buy specifically cake flour.
3/4 cup (or one and a half sticks) of butter, softened. So get this out of the fridge a half day or so before you plan on making the cake.
2 1/4 cup sugar
3 large eggs, at room temperature
6 tbs red food coloring
3 tbs unsweetened cocoa
1 1/2 tsp vanilla extract
1 1/2 tsp salt
1 1/2 cup buttermilk
1 1/2 tsp cider vinegar
1 1/2 tsp baking soda
If you're making the cake, grease and lightly flour three 9x2in round pans. Line with wax paper.
If you're making cupcakes, put cupcake liners in cupcake tin (will make 2 dozen).
Red Velvet here we come:
Pre-heat oven to 350 degrees.
In bowl #1 : sift cake flour and set aside.
In bowl #2: cream butter and sugar with an electric mixer. Cream for about five minutes until very light and fluffy.
Add eggs one at a time and continue to beat well.
In bowl #3: whisk food coloring, cocoa, and vanilla. Then combine with bowl #2.
In a measuring cup, stir salt into buttermilk. Add to bowl #2 in three parts, alternating with the cake flour. Beat until ingredients are incorporated, but do not over beat.
In bowl #4: mix the cider vinegar with the baking soda. This step makes you feel like a wacky scientist. Don't be surprised when the two start to pop pop and fizz fizz on you. Then add to bowl #2.
With a rubber spatula mix the dough well, scraping the sides making sure every part of batter is well-blended.
Divide into pans, or cupcake tin, and bake.
Cake will take 30-40 minutes.
The cupcakes should take about 12-15 minutes.
Use a cake-tester to test if you're not sure.