Preheat oven to 350° and grease an 8" springform pan with cooking spray.  Make cake: Place a small saucepan filled halfway with water over medium heat and bring to a simmer. Place bittersweet chocolate and butter in a heatproof bowl and set over the simmering pot, ensuring the water does not touch the bottom of the bowl. Stir until chocolate and butter are completely melted. Turn off heat and remove bowl from saucepan.  Dissolve espresso powder in hot water. Add sugar and espresso to melted chocolate and whisk until completely combined then add eggs and whisk to combine. Stir in cocoa powder.   Pour batter into prepared springform pan and bake until just set in the middle and a thin crust forms, about 35 minutes.   Let cake cool for 15 minutes, then remove sides of springform pan. Let cake cool completely.  Meanwhile, make ganache: Place heavy cream in a small saucepan and bring to a simmer. Place chocolate chips in a heatproof bowl, then pour hot cream over chocolate chips. Let sit 1 minute, then whisk to combine.  Pour ganache over cake and smooth with an offset spatula. Place in refrigerator until set, if desired, about 10 minutes.  Top with raspberries to serve.