Step 1

Prepare the whipped cream: Start whipping the cream (on low speed and gradually increase the speed to medium-high. Stop mixing when the cream starts taking shape and soft peaks form (they fall back). Cover and refrigerate until needed. The heavy cream should be very cold. I usually weigh the cream in the mixing bowl and refrigerate it, along with the beaters, while I prepare all the ingredients for the mousse.

Step 2

Prepare the chocolate ganache: Place the chopped chocolate in a large bowl (microwave safe). This will be the main bowl where everything will be added later on so it shouldn't be too small. Heat in the microwave in 20-second increments, stirring in-between, until melted. If you don't want to use the microwave, melt the chocolate over a double boiler.

Step 3

Heat the heavy cream until hot, but not boiling. I just pour the heavy cream into a microwave safe cup and heat it for about 20 seconds in the microwave. Heat it in short increments so it doesn't overheat and splatter everywhere.

Step 4

Pour about a third of the hot cream on the melted chocolate and gently stir using a spatula. Start by making circles in the center of the bowl and move outwards.

Step 5

Add the remaining cream in 2 additions and stir until completely smooth. Set aside while you prepare the pâte à bombe. Optional: If you notice that your ganache isn't very smooth, you can strain it through a fine mesh sieve into another bowl. Alternatively, you can use an immersion blender (make sure your bowl can handle it).

Step 6

Prepare the pâte à bombe: Pour the water into a round-bottomed stainless steel bowl and carefully add the sugar. Try not to get any on the sides of the bowl. Using a round-bottomed bowl will make it easier to scrape the sides and bottom so that the egg yolk doesn't coagulate. I use a stainless steel mixing bowl so that I don't have to transfer the mixture later on. Briefly whisk together then add the egg yolks and whisk again until combined.

Step 7

Place over a pot of simmering water (without touching). The water shouldn't be boiling or the eggs will curdle. Heat on medium-low, stirring constantly with a heatproof spatula, until the mixture registers 82°C (180°F) on a digital thermometer, about 7 minutes. Be sure to scrape the sides and bottom of the bowl frequently, to prevent any egg yolk from overcooking. The quantity is quite small so it can be a bit tricky to check the temperature. It's best to use a bowl with a narrow bottom so that the layer of pâte à bombe isn't too shallow. Tilt the bowl slightly before inserting the thermometer, if needed.

Step 8

Remove from the heat and using a hand-mixer, immediately start whipping on medium speed. Transfer to a mixing bowl first, if needed. The pâte à bombe is ready when: the mixture lightens in color, thickens, increases in volume and reaches the ribbon stage. This will take about 5 minutes. Don't keep mixing for too long past this point. If the pâte à bombe cools down too much, it will be harder to combine with the other components.

Step 9

Briefly stir the chocolate ganache with a spoon and check the temperature. The chocolate should be at a temperature of about 40°C (104°F) to 45°C (113°F). If necessary, reheat it in the microwave in 10-second increments, stirring in-between until it reaches the desired temperature. Tip: Don't skip this step. It's important in order to get a smooth chocolate mousse. If the chocolate isn't at the right temperature, your mousse might end up grainy.

Step 10

Fold the pâte à bombe into the chocolate ganache, just until combined. You'll hear the wonderful foamy, mousse sound. Don't forget to mix in the chocolate which is at the bottom of the bowl!

Step 11

Fold in the whipped cream, in 3 additions, just until incorporated, being careful not to deflate the chocolate mousse. You can briefly mix the whipped cream again if you feel like it deflated while chilling.

Step 12

Once fully combined and homogeneous, pour the chocolate mousse into desired cups. It will start to set quickly so don't leave it in the mixing bowl for too long.

Step 13

Refrigerate for 12 hours. If you are too eager to try it out, give it at least 4 hours for it to set! Serve with whipped cream if desired.