Measure out the ingredients for the mousse mixture but do not combine yet-measure out all the sugar, 1/4 cup of water, 1/2 cup of whipping cream, 2 Tbsps butter, 2 Tbsps Irish Whiskey. Then measure out the espresso powder, the gelatin and the other 2 Tbsps water. Set out a pastry brush and a cup of water.Reserve the other 1 1/2 cups of whipping cream and the Baileys for the topping.
Stir the sugar and 1/4 cup of water in a stainless steel saucepan over low heat until the sugar dissolves and the liquid is clear. Increase the heat and boil without stirring until the syrup turns a deep golden colour. Periodically swirl the pan and then dip the pastry brush in a cup of water and brush down the edges of the pan where the syrup swirled up the edge of the pan. (This took about 12 minutes for me).
When the syrup is a deep amber colour add the 1/2 cup of cream and the butter. The mixture will explode and bubble up. Stir until the butter melts and mixture is well combined. Remove saucepan from the heat. Measure out 6 Tbsps of the caramel and set aside in a small ramekin. Add the Irish whiskey to the caramel in the pot, stir and pour into a bowl.
Heat the 2 Tbsps of water remining and the coffee powder so the coffee dissolves. Don't make it too hot- just enough to melt the coffee granules. Sprinkle the gelatin over the coffee mixture and allow to stand about 10 minutes to soften. Then warm the mixture in the microwave gently- about 15 seconds on medium heat.
Stir the gelatin to mix well and stir it into the caramel mixture in the bowl. Put a few inches of cold water in the bottom of your sink and allow the caramel bowl to sit in the cold water for about 10 minutes stirring occasionally. You want the mixture to be cool but not fully set.
Meanwhile beat the remaining 1 1/2 cups of whipping cream in a separate bowl to soft peaks. Measure out 2 cups of the whipped cream and fold it into the caramel mousse mixture until it is well blended. Divide the mousse mixture between 6 serving glasses or dishes. Leave the extra whipped cream in the bowl.
Add 2 Tbsps of the Baileys to the whipped cream remaining in the bowl and continue to beat until it is stiff. Pipe or spoon the whipped cream over the mousse in the serving glasses. Cover and refrigerate at least 3 hours or up to a day.
Set aside the 6 Tbsps of caramel and remaining 2 Tbsp of Baileys until ready to serve. Gently warm the caramel about 15 seconds on medium low in the microwave just till it is pourable. Drizzle the caramel over the 6 serving glasses and then drizzle with a bit of Baileys. Serve immediately.