• Preheat oven to 350º F. Line muffin tins with paper cupcake liners.
• Place the butter, water, and cocoa in a small saucepan and heat gently, without boiling, stirring until melted and smooth. Remove from heat and let cool slightly.
• Beat together the eggs, buttermilk, vanilla extract, vinegar and beet juice until frothy. Beat in the butter mixture. Sift together the flour, cornstarch and baking powder, then stir into the
• mixture with the superfine sugar.
• Pour batter into prepared pans and bake for 25-30 minutes, or until toothpick inserted comes out clean.
• Cool in pan for about 10 minutes, then place on a wire rack and cool completely before frosting.

For the frosting:

• Using a clean towel and some lemon juice or vinegar, clean all equipment and utensils to be used for preparing the meringue..
• Fill a heavy duty pot about a quarter of the way with water and place on the stove over medium heat to simmer.
• Add egg whites and sugar to the mixing bowl and place on top of the pot, ensuring the bottom of the bowl is not in contact with the water in the pot. Lightly whisk the sugar egg white mixture constantly until temperature reaches 160°F.
• Once at the correct temperature, remove from heat and transfer mixing bowl to the stand mixer. With the whisk attachment, begin to whip the meringue until it is thick, glossy, and the bottom of the bowl is no longer warm to the touch. Do not begin adding butter while the bowl is still warm.
• Switch from your whisk to paddle attachment and with mixer on low speed, add butter cubes, one at a time, until incorporated. Continue to mix until it has reached a silky smooth texture.
• Add emulsion vanilla beans and salt and continuing to beat on low speed until well combined.