Melt the chocolate with the coffee in a water bath or in the microwave. Stir until homogenized and leave it to cool.
Start beating the confectionery cream until you get stiff tips. Add 1/3 of the melted chocolate and carefully stir with a spatula.
Once it homogenizes, add the rest of the chocolate and stir lightly once again. Don't stir too much or your mousse will deflate.
You can spray it into dessert cups or serve it with other desserts.