Pour 2 ¼ cups heavy cream into a medium sized saucepan and put on low-medium heat for about 5 minutes without stirring. Do not allow the cream to boil.
Once you see small bubbles appearing on the sides of the pan, take the pan off the heat and stir 1 teaspoon vanilla paste until well incorporated. Set this aside.
In a large bowl, whisk 5 egg yolks and ¼ cup sugar until combined. Gradually add the hot cream and whisk continuously to avoid scrambling the eggs. Add 3 tablespoons Irish cream and whisk some more.
Pour your mixture into 4 6-ounce ramekins (see notes). Put the ramekins into a deep baking dish or roasting pan. Pour hot water into the roasting pan until it covers about ¾ up the sides of the ramekins.
Bake for 30-40 minutes or until the custard is set - firm but still wobbly in the centre.
Take out of the oven and cool slightly before refrigerating for at least 3 hours (and up to 3 days).
When you're ready to caramelize, take the ramekins out of the fridge and wipe off any condensation that may have accumulated. Sprinkle about 1 tablespoon of granulated sugar on top and tap around gently to make sure that the sugar is evenly distributed and that you have an even layer.
If using a blow torch, melt the sugar until you get a nice crispy layer on top. Cool slightly before serving. If using the broiler, put your ramekins on a baking sheet and the baking sheet on the highest shelf of your oven. Broil on high until the sugar has caramelized. You may need to refrigerate again to cool the custard before serving.
You can use smaller-sized ramekins if you plan to serve more people. Just watch your baking time.
You can use the same amount of vanilla extract - you just won't get those nice specks of vanilla beans in the custard. You can also opt to use 1 vanilla bean - cut in half, put in with the cream while you're heating it, then scoop out before you mix the hot cream with the eggs.
If you want a boozier dessert, add a few more teaspoons of Baileys.