Heat all the ingredients in a large saucepan.

Bring to a boil while stirring with a whisk. Be careful of a boilover.

Keep an eye on the sauce and stir frequently.

Taste a spoonful (let it cool first!) and add more coffee powder if desired

Allow the sauce to reduce to a syrup that's still pourable.

Cool and transfer to a container. (I like a squeeze bottle)

Keep in the fridge and use within a month.