Allow ice cream to soften, about 30 minutes, and bring butter to room temperature, about 2 hours
Blend butter, sugar, and spices in large bowl
Add to ice cream and freeze
Heat cream soda in a pot until warm but still carbonated (at least 3 minutes). You could also just go with the very cold cream soda (my preference) and have a more frozen/slushy drink.
Fill each glass with a scoop of ice cream mixture and pour warmed or chilled cream soda over ice cream
Serve!