Preheat oven to 350°F. Place 7 liners in each of two 12-cup muffin pans.
In a bowl, whisk together flour, cocoa, baking soda, and salt.
In a glass measuring cup, combine buttermilk and vinegar.
In a bowl using an electric mixer, combine Splenda Sweetener, applesauce, and oil; mix on low speed until blended. Blend in eggs. Carefully add red food coloring and vanilla extract and mix on low speed.
Add half of the dry ingredients and half of the buttermilk mixture; mix on low speed just until combined. Add remaining dry ingredients and buttermilk and mix to blend.
Fill muffin cups 3⁄4 full with batter.
Bake for 20 minutes or until a wooden pick inserted into a cupcake comes out clean.