This authentic, rich dark chocolate mousse, with the added earthiness of black trumpets, makes an amazing dessert as is, but is only elevated when used to fill pastries and cakes.
Bring cream to a simmer and add dried mushrooms. Let it soak overnight. You will lose some volume to the mushrooms so add a bit more than you need for the recipe.
The next day, strain the mushrooms
Decant the cream to make sure there is no sediment, then whip the cream.
Combine chocolate and butter and melt over a water bath
Whip egg yolks and half the sugar to full volume
Whip egg whites, cream of tartar, and the remaining sugar to full volume
Fold egg whites into egg yolks
Fold butter-chocolate mixture into egg-sugar mixture