Dissolve the coffee in the hot water; then add the chocolate, coffee, half & half, and rum extract to a double boiler.
Stir until the chocolate has melted; then set aside and allow to cool slightly. Once lukewarm, whisk in the egg yolks and set aside and allow to cool thoroughly.
Next, add the egg whites and sugar to a bowl and beat with an electric mixer until stiff peaks have formed.
Fold in a spoonful of the chocolate mixture into the egg whites until blended, then add the remaining chocolate into the egg whites. (Be careful not to mix too hard so that the egg whites loose their stiffness).
Place the mousse in dessert cups and refrigerate for at least 1 hour so it has time to set; then garnish with fresh raspberries(optional).