4 egg yolks
1/4 c. brewed coffee, cooled (or 1/4 c. water and a heaping spoonful of instant coffee)
pinch of kosher salt
3 tbsp. sugar, divided
6 oz. semisweet chocolate, chopped, or chocolate chips
2 egg whites
1/2 c. heavy cream
Cinnamon Whipped Cream
1/2 c. heavy cream
2 tsp. sugar
1/4 tsp. cinnamon
1/3 c. almonds
1/3 c. cashews
1/3 c. pistachios
2 tbsp. light corn syrup
1 tbsp. sugar
1/2 tsp. kosher salt
1 tsp. chili powder
For the mousse, combine egg yolks, coffee, salt, and 2 tbsp. sugar in a heatproof bowl (metal or ceramic). Set over a pan of simmering water (make sure the bowl doesn't touch the water). Whisk constantly until the mixture lightens in color, becomes frothy, and about doubles in volume, 2-4 minutes. Remove the bowl from the pan and add chocolate. Whisk until melted and smooth. Put the bowl on a rack and cool to room temperature.
In a medium bowl, beat the egg whites until foamy. Add 1 tbsp. sugar and beat on high until there are firm peaks. Set aside.
In another medium bowl, beat cream until stiff peaks form.
Fold the egg whites into the chocolate until combined, then do the same with the whipped cream. Don't overdo it with the folding or your mousse will lose that airy texture. A few threads of white are fine.
Divide among six ramekins and chill until firm, at least 2 hours and up to one day ahead.
For the cinnamon cream, put cream, sugar, and cinnamon in a medium bowl and beat until soft peaks form.
For the nuts, preheat oven to 325º. Line a baking sheet with nonstick foil. Combine all ingredients in a medium bowl and toss to coat. Spread on the baking sheet and bake until the nuts are golden and the mixture is bubbling, about 15 minutes. Remove and cool completely on the baking sheet. Break into large or small shards.
To serve, top each mousse with a dollop of cinnamon whipped cream and garnish with the nuts.