• Preheat oven to 350 F degrees (175 C degrees ) and place rack in center of oven.
• Line and grease sides of two 8" or 9" pan.
• In a mixing bowl sift together the flour, salt, and cocoa powder, set aside.
• In bowl of your electric mixer, or with a hand mixer, beat the butter until soft (about 1-2 minutes).
• Add the sugar and beat until light and fluffy (about 2-3 minutes).
• Add the egg, beating well.
• Scrape down the sides of the bowl.
• Add the vanilla extract and beat until combined.
• In a measuring cup whisk the buttermilk with the red food coloring.
• With the mixer on low speed, alternately add the flour mixture and buttermilk to the butter mixture, in three additions, beginning and ending with the flour.
• In a small cup combine the vinegar and baking soda.
• Allow the mixture to fizz and then quickly fold into the cake batter.
• Pour batter into prepared pans.
• Bake in the preheated oven for approximately 30 minutes, or until a toothpick inserted in the center of the cakes comes out clean.
• Let the cakes cool for about 5 minutes in the pan before inverting them in a wire rack to cool completely.

FOR THE CAKE FROSTING:

• Beat cream cheese and butter until free of lumps, add sifted confectioner's sugar and beat until smooth.
• Add double cream or all-purpose cream and vanilla extract.
• Continue beating until smooth and creamy.
• And using Wilton 1M tip or 2D tip, pipe roses on the sides first then on the top, do the edges first and work your way in.