Sprinkle gelatin over the cold water in a small bowl. Let it sit for 5 minutes until it looks spongy.

In a saucepan, add heavy cream, milk, sugar, and salt. If using a vanilla bean, split it, scrape the seeds into the pot, and drop in the pod too. Heat over medium-low until the sugar dissolves and the mixture is hot but not boiling.

Remove the pot from heat. Take out the vanilla pod if using. Stir in the bloomed gelatin until fully dissolved.

Add vanilla extract if you didn’t use a bean. Taste the mixture to ensure it is lightly sweet and cozy with vanilla.

Pour the mixture through a fine mesh sieve into a measuring cup with a spout to remove any undissolved bits.

Divide the mixture into 6 small glasses or ramekins. Let cool at room temperature for 15 minutes, then cover and chill at least 4 hours, preferably overnight.