To make the cake, spray a bundt cake pan with cooking spray and dust lightly with unsweetened cocoa powder. Preheat the oven to 350ºF.

In a large bowl, combine the flours, sugar, baking soda, salt, cocoa, and cinnamon. Add the yogurt, vanilla, balsamic vinegar, water, orange juice, and zest. Beat with a mixer on low speed just until well-combined, about 1-2 minutes. Pour the batter into the prepared pan.

Bake 30-40 minutes or until a toothpick inserted in the center of the cake comes out clean. Cool in the pan 10 minutes before carefully inverting onto a serving platter to cool completely.

To make the ganache, put the chocolate, butter, and sugar in a heatproof bowl.

In a medium saucepan, bring cream to a boil and immediately pour it over the chocolate. Let sit for 1 minute, then whisk slowly until chocolate and butter are melted and the ganache is smooth.

Cover and refrigerate until the ganache has thickened to a frosting consistency, about 30 minutes. Using about half the ganache, frost the cooled cake. Store leftover ganache in the refrigerator for up to 1 week or freeze for future use.