Butter-infused Rum / Bacon-infused bourbon.
The fat or oil is used to bind with impurities in the alcohol and remove them. A flavored fat will also impart flavor to the alcohol.
10g molten butter + 1 cup of rum, or 10g bacon fat + 1 cup bourbon.
Immersion blend.
Leave to infuse at room temperature for 12 hours or more, according to desired flavor concentration.
Freeze until fats solidify
Strain through coffee filter, or other ~20 micron filter.
Other possibilites:
Blue cheese
Nut butters / oils.
Other fats