Top the granita with a hefty portion of whipped cream; you'll need the mild sweetness of the cream to balance the strong espresso. If you're cutting down on caffeine, you can use decaffeinated espresso beans instead of regular.
Granita Tips
For extra speed, buy the espresso ready-made from a coffee shop.
You can put the warm espresso directly into the freezer, but it will take much longer to freeze.
Granita will freeze faster in a metal pan, but you can use Pyrex; just allow more time. Or freeze the liquid in metal bowls.
Stir the granita with a fork to get a nice fine grain.
Granita melts quickly, so serve it in bowls or glasses that have been chilled in the freezer.