Preheat the oven to 325 degrees. Coat a doughnut pan with non-stick spray. In a large bowl, combine the flour, cocoa powder, baking soda, and salt. In a separate, smaller bowl, mix together the buttermilk, brown sugar, eggs, melted butter, and vanilla. Pour the wet ingredients into the dry and use a rubber spatula to gently mix the ingredients together. Lastly, mix in the chocolate chips.

Pour the batter to a large gallon size Ziploc bag; cut off a small corner and use the bag to pipe the doughnut cake batter into the pan, filling each well about 2/3 full (for bigger sized doughnuts; you can experiment but be careful not to overfill each well or cavity). Bake for 10-12 minutes, or until the cake tops spring back when touched. Cool completely on a wire rack.

Place the chocolate pieces in a small bowl. Combine the heavy cream and vanilla extract in a small saucepan over medium-low heat. Cook until small bubbles appear on the outside edge of the cream. Pour the hot cream mixture over the chocolate. Using a wire whisk, gently stir until all of the chocolate is melted and the mixture is smooth.

Once the doughnuts have cooled a bit, dip each one into the ganache, swirl a little to ensure good coverage and then place back on the wire rack. Sprinkle or decorate with nuts and/or any kind sprinkles and have fun!