Ingredients
Cupcakes:
1 1/2 cups self-rising flour
1 1/4 cups all-purpose flour
1 cup (2 sticks) unsalted butter, softened
2 cups sugar
4 large eggs, at room temperature
¾ cup eggnog
¼ cup milk
1 teaspoon vanilla extract
Spice Rum Buttercream:
5 large egg whites
11/2 cup sugar
4 sticks unsalted butter, diced and softened
1/4 teaspoon salt
½ cup spiced rum
Preparation
To make cupcake: Measure out flour and set aside. Add sugar and butter in a bowl and cream on medium speed until fluffy, about 3 minutes. Add eggs in 1 at a time, beating well after each addition. Add the dry ingredients in 3 parts, alternating with the eggnog and vanilla to start. Mix after addition until incorporated-do not overbeat. Fill cupcake liners about 3/4 full and bake for 20 to 25 minutes. Transfer cupcakes from tins to cooling rack. Allow cupcakes to cool completely before frosting. To make Spice Rum Buttercream: Combine egg whites and sugar in a bowl placed over simmering water. Bring mixture to 160 degrees F while whisking constantly. Transfer mixture to stand mixer bowl, fitted with a whisk attachment and beat on medium high speed (speed 8 on a KitchenAid stand mixer) until mixture cools and doubles in volume and forms stiff peaks; about 10-12 minutes). Add butter in one piece at a time, mixing to incorporate after each addition. The mixture may appear clumpy and almost curdled looking at first-this is normal. Keep mixing and it will become even and smooth again. Add salt and spiced rum and mix to combine.
