Lighter Red Velvet Cupcakes

Preheat the oven to 350 °F. Line a 12-cup muffin pan with cupcake liners or coat with cooking spray. To make the cupcakes, combine the flour, cocoa powder, baking powder, 1/2 teaspoon salt, and baking soda in a large bowl. Whisk together the buttermilk, 3/4 cup sugar, oil, egg, and food coloring in a medium bowl until well mixed. Gradually stir the buttermilk mixture into the flour mixture just until incorporated. Fill each muffin cup two-thirds full with the batter. Bake until a toothpick inserted into the center comes out clean, about 20 minutes. Let cool in the pan on a rack 10 minutes. Remove the cupcakes from pan and let cool completely on the rack. Meanwhile, to make the Marshmallow Cream, bring a few inches of water to a simmer in a saucepan that can hold a large heatproof bowl above the water. Whisk the remaining 3/4 cup sugar, egg whites, rum, cream of tartar and 1/8 teaspoon salt in the bowl by hand. Set the bowl above the simmering water and beat with an electric hand mixer at medium-high speed until stiff peaks form, 5 – 7 minutes. Remove from the heat. Let cool 5 minutes. Evenly spread the frosting over the tops of the cupcakes.