Add the coffee to a large mug. Add the butter, erythritol, and spices, then stir to combine. You may add more or less sweetener and spices to suit your personal tastes.
Step 2
Add the rum to the buttery coffee mixture. Stir well to combine. You may add more or less rum as desired.
Step 3
Carefully take a handheld stick blender and blend the coffee until smooth and foamy on top. Alternatively, you may prepare the coffee in a free-standing blender, blending until velvety smooth, and foamy. Taste and adjust flavorings as needed and serve hot.