Preheat the oven to 325°F.
Pour the cream, coffee, Irish cream, and salt into a small saucepan. Place the pan over medium-low heat and heat the cream mixture until steam gathers on the surface and it is hot to the touch. Don't let the cream come to a boil.
1½ cups heavy cream, ¼ cup strong black coffee, ¼ cup Irish cream, ¼ tsp kosher salt
While the cream mixture is heating up, whisk to combine the egg yolks and ½ cup of the sugar. Whisk until the mixture turns a lighter shade of yellow.
5 large egg yolks, ¾ cup superfine sugar **
Once the cream is hot, slowly pour the cream mixture into the yolk mixture while whisking constantly to temper the eggs. Once the cream mixture is fully integrated, pour the resulting mixture into a pitcher through a fine-mesh strainer.
Arrange 5 ½ cup ramekins inside a 9x13 roasting pan. Pour the mixture into the ramekins leaving a little space at the top of each. Fill the roasting pan with boiling water until the water reach halfway up the sides of the ramekins. Transfer the roasting pan to the oven and bake for 40-45 minutes. The Crème Brûlée should be set but still wobbly.
Take the ramekins out of the water bath and place them in the fridge. Let the crème brûlée chill for a minimum of 2 hours or for up to 3 days. ***
Dust the surface of each crème brûlée with the remaining sugar. Shake off the excess and torch the sugar with a culinary torch until caramelized. Let sit for 5 minutes before serving for the sugar has a chance to cool and solidfy into the crisp crust we all know and love.
¾ cup superfine sugar **