Position a rack in the center of the oven, and preheat to 350°F.
Put shortening, sugar, cocoa, food coloring, flour, salt, vanilla, baking soda and vinegar in the bowl of a stand mixer fitted with the paddle attachment. (You can use a hand mixer if you allow the shortening to soften at room temperature before beginning.) Mix to combine, starting at low speed, then raise the speed to low-medium and mix for about 1 minute. Add the eggs one at a time, mixing for 1 minute after each is absorbed into the mixture. Add the buttermilk in two portions, stopping to scrape the sides of the bowl between additions.
Grease two 9-inch cake pans (2 inches deep) with the butter, and flour them.
Divide the batter evenly between the two pans, using a rubber spatula to scrape down the bowl and get as much batter as possible out.
Bake until the cakes begin to pull from the sides of the pans and are springy to the touch, 35-40 minutes.
Remove cakes from the oven and let cool for at least 30 minutes, preferably 1 hour. The cakes should be at room temperature before you remove them from the pan.
Put a piece of parchment paper on a cookie sheet, sprinkle with sugar, and one at a time, turn the pans over and turn the cakes out onto the parchment; the sugar will keep them from sticking.
Refrigerate or freeze until ready to decorate with Cream Cheese Frosting.