For the moussee
Combine the egg yolks and 75 gr. of the sugar in a mixer bowl and whisk until thoroughly blended. Place the bowl over simmering water and heat, whisking constantly, until the mixture is thickened and very foamy and has reached 70⁰C. Transfer the yolk and sugar mixture to the mixer and whip on high speed with whip attachment until cool. Melt the gelatin in a bain marie and add the espresso and coffee liquor. Pour the gelatin mixture in to the yolk mixture and incorporate. Meanwhile, make an Italian meringue with the egg whites and the remaining 100 gr. of sugar. . Fold the meringue into the egg yolk-sugar mixture into until incorporated. Do the same with the whipped cream. Continue to fold until all components are fully incorporated. Pour the mousse into a serving dish of your choice and refrigerate until completely set.