Gingerbread Cupcakes with Eggnog Buttercream Frosting

Preheat oven to 350°F. Line a standard cupcake pan with 9 paper liners.
In a large bowl or stand mixer, cream together butter and brown sugar. Mix in egg and vanilla. Scrape bowl as needed. Add spices, salt and baking soda, mixing until just dispersed. Add molasses, mixing until just combined. Lastly, with mixer on low, alternate additions of flour and milk. Continue mixing until no streaks remain.
Divide batter equally between prepared liners, using a large cookie scoop. Liners should be roughly 2/3 full.
Bake for 18-20 minutes or until a toothpick inserted comes out with a few moist crumbs. Do not over bake. Cool in pan until easy to handle. Transfer cupcakes to a wire rack to cool completely.
In a large bowl or stand mixer, beat butter until light and fluffy. Add in optional rum extract and nutmeg. Add powdered sugar in small batches, mixing well between additions. With mixer on low, slowly drizzle in eggnog. Mix until fully combined. Transfer frosting to a large piping bag fit with a piping tip. Pipe as desired.
Store cupcakes in an airtight container for up to several days or refrigerated and brought to room temperature prior to eating.