How to make coffee-infused butter?
A simple way to do this is to place 250 grams of whole bean coffee and 500 grams of butter in a ziploc bag.  Then place that in a water bath with a sous vide device set at 90C.  Cook for 3 hours.  Alternately, you can do this on the stove top.  Very low heat, same amount of time.  The longer you cook, the stronger the coffee flavor.  Strain, discard beans, use the butter.  Credit to an old ChefSteps formula.