For Cake

1. Preheat oven to 350°F.
2. Grease four six inch cake pans with non-stick cooking spray and line bottoms with parchment paper circles.
3. Place the bittersweet chocolate in a small bowl and cover with hot espresso and hot water. Cover bowl with plastic wrap and set aside.
4. In a medium bowl, combine yogurt, milk, canola oil, eggs and vanilla. Whisk to combine.
5. In the bowl of a stand mixer fitted with a paddle attachment, mix together flour, sugar, cocoa powder, baking soda, baking powder and salt on low speed until well combined.
6. Put mixer on low speed and slowly add the yogurt mixture.
7. Mix on medium speed for just 30 seconds until well combined.
8. Unwrap the chocolate and hot espresso mixture and stir until smooth.
9. Slowly pour the melted chocolate into the mixer and mix on low speed until incorporated.
10. Remove the bowl from the mixer and scrape down sides and bottom of bowl with a rubber spatula to be sure batter is well combined.
11. Pour batter evenly into the prepared pans, weighing each pan using a kitchen scale to be sure they are equal.
12. Bake on center rack of the oven for 25-30 minutes or until a toothpick inserted in the center comes out clean.
13. Remove from the oven and let cool on a wire rack for 30 minutes before removing the cakes from pans. Cool completely before assembling the cake layers.

For Chocolate Mousse

1. While cake layers are baking, make the mousse.
2. In a small bowl, dissolve the cocoa powder with the hot water and set aside to cool slighty.
3. In a medium bowl set over a double boiler, melt the chocolate chips until smooth and shiny.
4. Remove from heat and set aside to cool slightly.
5. Once chocolate has cooled a bit, add the heavy whipping cream to the bowl of a stand mixer fitted with a whisk attachment.
6. Add sugar and whisk on high speed until firm peaks form.
7. Stir together the melted chocolate and dissolved cocoa powder.
8. Add half of the whipped cream to the chocolate mixture and fold gently to combine.
9. Add the remaining whip cream and continue folding with a rubber spatula until fully incorporated.
10. Do not over mix.
11. Chill the mousse until the cake layers are cool enough to assemble.

For Ganache

1. Heat heavy whipping cream over medium heat until it begins to simmer. Do not boil the cream.
2. Place chocolate chips in a heat safe bowl and then pour the hot cream over the top.
3. Let stand for 2-3 minutes and then whisk together until smooth.
4. Allow ganache to firm up for 10-15 minutes before pouring over the chilled cake.
5. Use an offset spatula to spread the ganache over the top and down the sides of the cake, spreading evenly.
6. Garnish cake with sugared cranberries and rosemary sprigs if desired.