Preheat oven to 350 degrees F. Spray a budnt pan with cooking spray with flour (or you can coat the sides with butter or spray and then flour - just make sure you get every inch of that pan!)
Place unsweetened chocolate squares and cocoa powder in a medium bowl, and pour the boiling water over the top. Stir until melted and well-combined, then set aside.
In another bowl, combine the flours, baking soda, and salt. Set aside.
In the bowl of a stand mixer, beat the butter on high speed until creamy, about 1 minute. Add brown sugar and mix for another 2-3 minutes or until light and fluffy. Scrape sides of mixing bowl. At medium-high speed, add eggs one at a time, mixing for about 30 seconds in between each addition. Scrape sides of bowl again, then add creme fraiche and vanilla and beat for another 30 seconds or until incorporated.
With the mixer on low speed, add ⅓ of the flour mixture, then add half of the chocolate mixture and mix to combine. Repeat ending with the flour mixture being careful not to overbeat. Remove the bowl from the mixer, scrape sides and mix well by hand until incorporated.
Pour the batter into the bundt pan, evening out the top of the batter with a spatula. Bake on the middle rack for 40-50 minutes or until a skewer or toothpick comes out clean. Remove from oven, rest in pan for 10-15 minutes then invert onto a cooling rack and cool completely. While cake is cooling, make the ganache and the caramel sauce.