Prepping the Butter:
Leave the other ½ cup butter out on the counter to bring it to room temperature. If the butter is rock solid (usually from the freezer) I stick it back in the microwave for 10 seconds to get it workable again. See notes for more info.
Dough Part One:
Preheat the oven to 350 degrees. With an electric mixer (I usually just use a hand-held one), cream the melted/solid butter, room temperature butter, sugar, and vanilla until creamy and fluffy. Add the eggs and mix until just incorporated.
Dough Part Two:
Add the flour mixture to the creamy butter mixture and mix until incorporated, adding the coffee gradually as you go. The dough should be thick and sticky, but dry enough to touch with your hands without making a huge mess. If it's still too sticky, add more flour. Stir in the chocolate chips.