Grease a 10- to 12-inch Bundt pan with butter and dust with dark cocoa powder. Set aside.

In a bowl, whisk together the flour, black cocoa and salt until well-combined.

In a stand mixer fitted with the paddle attachment, cream the butter and sugar, scraping the sides of the bowl as needed, until light and fluffy, about 10 minutes.

Add the eggs one at a time, allowing each to fully incorporate before adding the next. Add the yolks, orange liqueur, vanilla and orange zest, and mix to combine.

Add the flour mixture and mix, scraping the sides of the bowl as needed, until just combined.

Pour the batter into the prepared pan and gently tap the pan to level out the batter and remove any air bubbles.

Place the cake into a cold oven, then set the temperature to 300 F and bake until a cake tester comes out clean when inserted into the center of the cake, about 1½ hours.

Let cool in the pan for 30 minutes, then invert onto a wire rack to cool completely.

Place both chocolates in a heatproof medium bowl.

In a small saucepan, heat the cream over medium heat until it steams. Pour the hot cream over the chocolate, cover with plastic wrap and let sit for 5 minutes.

Uncover and whisk the chocolate and cream until smooth. Add the orange liqueur and orange extract and whisk to combine.

Transfer the cake to a serving platter or cake stand and pour the ganache evenly over the top and garnish with the orange zest.