Preheat oven to 350 degrees and spray mini bundt pans with non-stick spray.
Melt chocolate in microwave and put in a bowl. Whisk in the oil and sugar until smooth. Whisk the coffee and buttermilk to chocolate mixture. In a separate bowl, mix together flour, cocoa powder, baking soda and salt. Add half the dry ingredients to the wet ingredients. Add remaining dry ingredients and stir until smooth. Pour the batter into pans and bake for 20-25 minutes, or until a toothpick inserted in center of cake comes out clean. Let cool completely and then pour glaze over.
Whisk blackberry puree and confectioners' sugar together and drizzle over cakes