Preheat your oven to 350 F and line a 9x12 inch baking pan with parchment paper.

In a mixing bowl, combine the flour, cocoa powder, baking soda, salt, and sugar using a whisk.

In a separate bowl combine the buttermilk, egg, applesauce, oil, vanilla, and vinegar until fully (or almost fully) mixed.

Combine the wet mixture with the dry and incorporate using a spatula. Using fully mixed, add enough red food colouring until the batter is red. Finally, slowly pour in the hot water while mixing the batter until the batter is smooth and fully combined.

Pour the batter onto the pre lined pan and bake on the bottom rack for approximately 12 minutes or until toothpick comes out clean.

In a stand mixer, whip the cream cheese, vanilla, and powdered sugar on high for 1-2 minutes. Gradually add the heavy cream until the icing doubles in size and forms stiff peaks.