Cream shortening, sugar, and eggs until light and fluffy.

Create a paste by mixing red food coloring and cocoa powder.

Add the cocoa paste to the creamed mixture and blend well.

Gradually add buttermilk to the mixture, alternating with additions of cake flour and salt, until fully incorporated.

Stir in the vanilla extract.

In a separate small bowl, combine baking soda and vinegar; then, quickly blend this mixture into the batter.

Pour the batter evenly into 3 or 4 greased and floured 8-inch cake pans.

Bake in a preheated oven at 350°F (175°C) for 24-30 minutes, or until a toothpick inserted into the center comes out clean.

Remove the cakes from the oven and let them cool slightly before splitting the layers.

Prepare the frosting: In a saucepan, gradually add milk to flour, stirring continuously to avoid lumps.

Cook the flour and milk mixture over medium heat until it becomes very thick, stirring constantly.

Remove from heat and allow the mixture to cool completely.

In a separate bowl, cream together sugar, butter, and vanilla extract until the mixture is light and fluffy.

Add the cooled flour and milk mixture to the creamed butter mixture.

Beat the frosting at high speed until it is very fluffy, resembling whipped cream.

Fill and frost the cake layers with the prepared frosting.