Preheat oven to 200º F.
Spread espresso beans in a single layer onto a baking sheet.
Bake until lightly toasted and dried, about 1 hour.
Remove from the oven and grind in batches in a coffee or spice grinder until finely ground.
Pour into a container with a tight fitting lid, such as a small Mason jar or spice jar, and store for up to 6 months.
