To make the cake:

1. Preheat the oven to 350 degrees, and grease a 12 cup bundt pan with baking spray.
2. Whisk the coffee and both cocoa powders together until dissolved and smooth. Stir in the vanilla and set the mixture aside.
3. In a large mixing bowl, combine the sugar, salt, baking soda, eggs and egg yolk. Use a hand mixer on low speed to blend everything together until smooth.
4. Add the buttermilk, melted butter and oil and mix for another minute on low speed.
5. Add the flour and mix on medium speed for 2 minutes, until smooth and slightly thickened.
6. Add the coffee/cocoa/vanilla mixture and melted chocolate. Mix on low speed for one minute, and use a spatula to scrape the sides of the bowl and make sure there are no lumps or any unmixed patches.
7. Pour the batter into the prepared bundt pan and bake for one hour. Remove from the oven and allow to rest in the pan for 15 minute before inverting onto a cooling rack. Allow the cake to cool completely before glazing and serving.

To make the glaze:

1. Add the chopped chocolate, heavy cream and coffee to a heatproof measuring cup or glass bowl. Microwave on full power for 30 seconds. Remove from the microwave and stir vigorously to redistribute the heat and encourage melting. Return to the microwave for an additional 15 seconds, and stir again until melted and smooth.
2. If necessary, microwave again for 5 more seconds to finish melting everything together.
3. Pour chocolate glaze over the cooled cake and allow to set for at least 15 minutes before slicing and serving.