A popular Christmas libation sans the calories. The only cals are in the rum...
figure one cal per each “proof” of alcohol. 100 proof rum is about 100 cals per shot.
SKINNY HOT BUTTERED RUM
Mix tablespoon rum, teaspoon butter buds (in spice section), bit sweetener.
ASSEMBLY Add to cup of boiling water in pretty mug. Float 3-4 whole allspice on top.
SERVE HOT.
You can buy a mix found in a cold case usually near the Dairy or near the Liquor:

Or make your own:
https://www.allrecipes.com/recipe/78751/tom-and-jerry-mix/