Cupcakes: – 1/2 cup butter, softened to room temperature – 1/2 cup packed light or dark brown sugar – 1 egg, at room temperature – 1/2 cup milk, at room temperature – 1/2 cup molasses – 1 teaspoon vanilla extract – 1 and 1/3 cups all-purpose flour – 1/2 teaspoon baking powder – 1/2 teaspoon baking soda – 1/4 teaspoon salt – 1 teaspoon ground cinnamon – 1/2 teaspoon ground ginger – 1/2 teaspoon nutmeg – 1/4 teaspoon ground allspice