Preheat the oven to 400° Fahrenheit. Prep three cake pans.
In a large mixing bowl, cream together the butter at sugar for approximately five minutes
Add in the eggs, a little at a time.
In a small bowl, mix cocoa powder, vanilla extract, food coloring, and hot water until combine. Add into the large mixing bowl.
In a small bowl, combine buttermilk and salt. Alternate adding the buttermilk mixture and the flour to the large mixing bowl.
In a small bowl, mix the vinegar and baking soda. Add the to large mixing bowl and mix until smooth.
Quickly divide the cake batter into three pre-prepared baking pans and bake for 20-25 minutes or until fully cooked. Let cool for 5 minutes before turning out. Then let cool completely.