Instructions

1. Preheat oven to 325 degrees F. Grease and flour a 9x13 inch pan. 
2. Whisk the boiling water and cocoa powder together in a small bowl and set aside.
3. Combine the sugar, flours, baking soda and salt in the bowl of a stand mixer.  Use the paddle attachment for best results. 
4. Whisk briskly the oil, sour cream, eggs and egg yolks in a large bowl.
5. Add the oil mixture to the cocoa and water mixture and slowly stir to combine.
6. Turn the mixer on low speed and add the liquid mixture to the dry mixture slowly. Beat on low for one minute.
7. Stop and scrape down any unmixed mixture and continue to beat on low speed until the batter is smooth.
8. Pour the batter into the prepared pan and bake until the cake springs back when pressed around 35 minutes. 
9. Cool on a rack for 30 minutes, and then remove cake from the pan and cool completely before adding the ganache about 1 hour.
10. Make Chocolate Ganache: Put the chopped chocolate in a food processor or mixer. 
11.  Heat the heavy cream by microwave on high for 3 to 4 minutes (you want a simmer not a boil so watch it).
12. Pour the cream over the chocolate and let sit for around 2 minutes.
13. Pulse several times with the food processor or mixer until chocolate is smooth.
14. Use this for glazing your cake. If you want a whipped/ lighter type frosting, allow it to come to room temperature for around 2 hours. Then use a mixer to whip it for around 2-3 minutes.