Place your mixing bowl and beaters in the fridge to chill for 1 hour. This will speed whipping the cream.
Chop the chocolate into small pieces and set aside.
Pour 120ml (½ cup) of cream into a saucepan and bring to a gentle simmer. Keep an eye on the cream, you do not want it to boil. Remove from heat when you see bubbles form at the side of the saucepan.
Pour over the chocolate to the cream let it sit for a minute to soften the chocolate. With a spatula and metal spoon, gently stir until combined and the ganache is smooth and glossy,
Mix in 60 ml (¼cup) Baileys and leave the chocolate ganache to come to room temperature.
Whisk together gelatin and water in a small bowl and allow gelatin to bloom. Heat in the microwave for 15 seconds or until melted. Whisk gelatin into chocolate mixture.
In the bowl of stand mixture (or using a hand mixer) whip up 120 ml l of cream until it just holds medium peaks
Gently fold the whipped cream into the chocolate mixture. Transfer to serving glasses and ramekins. Refrigerate the mousse and let it set for about an hour.
Whip together 60ml cream, 30ml Irish cream and icing sugar until it just holds stiff peaks. Pipe or spoon onto mousse.