I used Palombini (now: Buscaglione) espresso pads from Italy, and tinctured them.
Just cut the pad open and used it's content (about 7 grams powdered) with about 30 ml of ethanol.
Shaken every day at room temperature, i started to use it after about 2 months.
Even so soon, it provided a very elegant, dark, roasted, chocolate spicy touch to some of my fragrance compositions.
Now, 3 months later it's even more intense.
The note lasts till the dry down base, where it adds to the spicy part.
Love it. Give it a try, it's inexpensive and wonderful.