Preheat your oven to 350°F and line two standard cupcake pans with paper (or silicone reusable) liners. You’ll get close to 18 cupcakes from this batter.
In a large bowl, cream the butter and sugar with an electric mixer (or a REALLY strong arm and whisk!) until light and fluffy – roughly 5 minutes. Add the eggs, one at a time, incorporating completely before adding the next egg.
In a separate small bowl, whisk together the dark rum, cocoa and vanilla. Add to the sugar/butter mixture and beat well. Add your red food coloring until it’s as red as you’d like.
Pour kefir into a liquid measuring glass and add salt. Stir until combined. Add to the kefir/salt mixture to the other liquid ingredients in three parts, alternating with the cake flour (one part kefir, mix, one part flour, mix, etc.). With each addition, beat until the ingredients are just incorporated, careful not to over mix.
In a small bowl, stir together the cider vinegar and baking soda. Add this mixture to batter and mix. Using a rubber spatula, scrape down the batter in the bowl, making sure the ingredients are well-blended and the batter is smooth, again careful not to over mix.
Pour batter into cupcake liners until 2/3 full (careful not to overfill, as these babies rise!). Bake 20-25 minutes, or until the tops spring back when you gently touch them.
Cool the cakes in the pan for 10 minutes, before removing from the pan to cool completely. When cool, frost with icing of your choosing and enjoy your Valentine’s Day treat!
Notes: Cake flour: This recipe calls for cake flour, which differs from regular all-purpose flour in many ways. Most notably, it is has a much finer grain, lending to extra fluffy baked goods. Substitute all-purpose flour if you have it on hand.
Butter: We suggest using organic, grass fed butter in this recipe for taste and health benefits. Substitute other butter you have on hand, melted unrefined virgin coconut oil, or the vegetable oil of your choice.