How to prepare this recipe
Step 1: Heat and Cool the Egg Yolks: In a heatproof bowl, whisk together the egg yolks and sugar until the color changes from bright yellow (Image 1) to pale yellow (Image 2) and the mixture thickens considerably. It should drip, like a ribbon, and then slowly disappear to a smooth consistency (Image 3). Add the orange liqueur.
Prepare the water bath. Place the mixture over a pan of not-quite-boiling water and continue whisking frequently until the mixture lightens in color and becomes too hot to touch.
Remove from the heat and continue stirring in a cold water bath until the mixture thickens again to that “ribbon” consistency. Set aside (Image 4).
Step 2: Melt the Chocolate: In a separate bowl, combine the chocolate, espresso and hot water. Place pan of hot water over top and whisk until dissolved (Image 5). Turn off the heat, then add the butter until incorporated (Image 6). Stir the melted chocolate into the egg yolk mixture (Image 7). Set aside.
TIP: If the chocolate starts to feel a little grainy or greasy, it may be stuck. But don’t worry, this is easily fixable. Simply add a teaspoon of cold water at a time until the mixture is smooth again before mixing it into the eggs.
Step 3: Whip the egg whites: In the planetary mixer, or with the electric mixer, whip the egg whites with a pinch of salt until soft peaks form. Then add the sugar and continue to whip until stiff (Image 8). Be careful not to beat too much!
Step 4: Add the egg whites: Gently fold in ¼ of the egg whites (yes, you can mix) until fully incorporated (Image 9). Then, gently fold in the remaining whites (Image 10) until only a few small streaks remain (here, be careful not to overmix) (Image 11).
Step 5: Cooling: Transfer the mousse to a large container (or individual molds or bowls), wrap with cling film and leave to cool for at least 4 hours, ideally overnight (Image 12). Serve with a pinch of flaked salt and whipped cream to taste. Enjoy!
Storage: Leftovers can be stored in an airtight container (or tightly wrapped) in the refrigerator for 2 to 3 days. However, I recommend serving it within 24 hours of preparation for the freshest flavor.
