Add about a fourth of the flour to the butter/sugar mixture and beat to combine.
Add about one third the buttermilk mixture and beat until combined.
Repeat above, alternating flour and coffee and ending with the flour mixture.
Fill 18 paper-lined muffin cups two-thirds full.
Bake at 350 degrees F for 15-20 minutes or until a toothpick comes out clean.
Remove to wire racks to cool completely.