1. Prep the Custard

In a mixing bowl, whisk together the egg yolks, sugar, and a pinch of salt until the mixture is smooth and pale. Next, add the vanilla bean paste and bourbon (if using), whisking until fully incorporated. 

Then, slowly add the whipping cream, continuing to whisk until the mixture is well combined and smooth.

2. Portion and Seal

Divide the custard mixture evenly into small mason jars or heat-safe canning jars, leaving some space at the top. There will be some air bubbles in the mixture. Cover the jars and let them rest until the air bubbles subside. 

Then, seal the jars with lids, but not overly tight—just enough to keep water out.

3. Set the Sous Vide

Fill a large pot or sous vide container with water and attach your sous vide precision cooker. Set the temperature to 180° F and place the jars in the water bath, letting them come up to temperature with the water

Once the water reaches the desired temperature, cook for 1 hour.

4. Chill the Custard

After 1 hour, remove the jars from the water bath and let them cool at room temperature for about 30 minutes.

Then, transfer the jars to the refrigerator and chill for at least 4 hours, or overnight, until fully set.

5. Caramelize the Tops

Just before serving, remove the custards from the refrigerator and uncover them. Sprinkle a thin, even layer of sugar over the top of each custard.

Use a kitchen torch to gently caramelize the sugar until it forms a crisp, golden-brown crust. Alternatively, you can place the jars under a broiler for a few minutes, watching closely to prevent burning.

6. Serve and Enjoy

Enjoy! Just be sure you let the caramelized sugar cool and harden for a minute or two before serving!