Fill mug up to the top with hot water and allow to temper for ~45 seconds.
Dump hot water and refill to 2/3 with hot water.
Add a heaping dessert spoon of Hot Buttered Rum Mix and stir vigorously.
Add Four Roses Bourbon and 1 dash of Angostura bitters.
Top with more hot water if needed and give a quick stir.
Garnish with grated nutmeg or a tall cinnamon stick, and serve with the spoon in.
Hot Buttered Rum Mix (El Camino-Louisville version):
1 lb butter at room temperature
6 cups brown sugar
4 tsp cinnamon
2 tsp grated nutmeg(fresh)
1 tsp ground cloves
1 tsp salt
Stir until evenly mixed.