Preheat oven to 350 degrees and prepare a bundt pan with cooking spray.
Place eggs and sugar in a double boiler over low heat. Whisk continuously until sugar is dissolved and the mixture reaches a temperature of 110-115 degrees. The eggs should not cook but should be warm.
After the mixture reaches 110-115 degrees, pour it into the bowl of a stand mixer. Use the whisk attachment and beat on high speed until the eggs become pale yellow and ribbon-like (about 4-5 minutes).
In a separate small bowl, combine the cocoa powder, hot coffee, and vanilla. Stir until the cocoa powder dissolves.
In a second small bowl, combine the flours, baking soda, and salt. Stir to combine.
Once the eggs are whipped, add the cocoa mixture, softened butter, baker’s chocolate and chocolate chips. Mix on medium speed until combined.
Next, add the flour and buttermilk to the bowl of the stand mixer, alternating between the two. Mix on low between each addition and scrape the sides of the bowl as needed.
Pour the mixture into the prepared cake pan. Tap the pan gently against the countertop to force air bubbles to the surface.
Place the pan in the preheated oven and bake for 35-45 minutes or until a toothpick inserted in the center comes out clean.
Remove the cake from the oven and allow to cool on a cooling rack.
After the cake is completely cool, remove it from the pan by turning it upside down on a serving plate.