PREP: Mise the recipe ahead of time.

1. Create 2 double boilers:

• Choose a small and a medium-size stainless steel bowl, each of which fits snugly into a saucepan with the bottom of the bowl at least 3 inches above the bottom of its saucepan.

2. Prepare egg yolks and egg whites:

• Separate the eggs, placing the yolks in the larger of the double boiler bowls and the whites in an additional clean, dry, grease-free bowl.  Take care that no yolk gets into the whites.  (If this happens, the whites will not hold air when beaten.)

3. Melt the chocolate:

• Chop or break the chocolate into small pieces and place it in the remaining double boiler bowl.
• Fill the bowl’s saucepan with about 1 inch of water.  Place the saucepan over low heat and then set the bowl of chocolate in it.  Stir and scrape the chocolate with a plastic spatula until it’s completely melted and smooth.  Don’t allow the chocolate to get too hot or to get even a drop of liquid in it, or it may seize up and become unusable.
• Remove the double boiler from heat and hold on the back of the stove.

4. Make coffee sabayon:

• Choose a bowl larger than the bowl holding the egg yolks.  Create an ice bath by filling the larger bowl ⅓ full of ice and adding a little water.
• Fill the remaining saucepan with about 1 inch of water.  Place it over low heat and bring the water to a bare simmer.
• Vigorously beat the step 4 sugar into the egg yolks until light and fluffy, and then whisk in the coffee and cognac.
• Fit the yolk mixture bowl into the saucepan of barely simmering water.  Whisk constantly for about 3 minutes until the mixture becomes foamy, thickens to a custard-like texture, and reaches a temperature of 135°F.  (If you test it with your finger, it should feel slightly too hot for comfort.)  Take care not to overheat it, lest it curdle.
• When the sabayon is thickened and hot, transfer its bowl to the ice water bowl and continue to whisk until barely warm.  Immediately remove from the ice bath; do not allow it to become cold.

5. Make the mousse base:

• If necessary, warm the butter for a second or two in a microwave oven, taking care not to melt it.
• Whisk the soft butter into the sabayon until smooth.  (If either ingredient is too cool, the mixture may appear curdled; that’s OK, as it will smooth out when the chocolate is added.)
• Ensure that the chocolate is still warm and fluid.  Scrape the chocolate into the sabayon mixture and whisk until smooth and thick.

6. Whip the egg whites:

• Use a clean, dry, grease-free whisk to whip the egg whites to a foamy consistency.
• Whip the step 6 sugar and the salt into the whites and then continue whipping vigorously to firm peaks.  Don’t overbeat to a stiff or crumbly texture.

7. Complete the mousse:

• Fold the beaten egg whites into the mousse base until until the mixture becomes light, fluffy, and homogenous in color. 

8. Fill glasses or ramekins with mousse:

• For help ensuring best appearance, transfer the mousse into a pastry bag (no tip needed).
• Cut off about ½ inch of the bag’s pointed end, and insert it into one of two serving glasses or cups.  Pipe half of the mousse into each glass.  (Alternatively, spoon or scoop the mousse into the glasses.)

HOLD:  Cover the glasses with plastic wrap and refrigerate up to 7 days

COOK! Finish and plate your dessert.

9. Wash the strawberries and blot dry on paper towels.

10. Make the Chantilly cream:

• Place a stainless steel bowl into the refrigerator for a few minutes until cold.
• Combine the cream, confectioner’s sugar, and vanilla in the chilled bowl.
• Beat with a whisk to firm peaks.
• Transfer the Chantilly cream into a pastry bag fitted with a star tip.
• Pipe a large rosette of cream covering the surface of each mousse.

11. Plate:

• Place each glass of mousse onto a plate lined with a beverage napkin. 
• Arrange the strawberries on each plate.
• Plant one or more cookies (depending on size) in the cream at the back of the glass.