Step 1

Pour 1/2 cup (125ml) of cold milk in a small bowl and sprinkle the gelatin granules over it in an even layer. Set aside for at least 5 minutes to allow the gelatin to soften.

Step 2

Spread the sugar in an even layer in a medium skillet or wide, deep saucepan. Warm the sugar over medium heat until it starts to liquify. (Generally it'll start to liquify in certain spots, depending on your pan.) When it starts to melt, gently stir the sugar with a heatproof utensil so it liquifies evenly. It will get grainy as you stir it, but as you continue to cook it, it should smooth out as it begins to take on a light amber color.

Step 3

Continue to cook the sugar, swirling the pan more than stirring it, until the caramel starts to smoke and is a deep amber color. Smell the caramel and when it just starts to smell smoky, turn off the heat and add the warm cream gradually, stirring, until it's incorporated into the caramel. If there are any lumps, continue to stir the mixture until the lumps are melted. (You may need to rewarm the mixture over very low heat to get them all melted.)

Step 4

When the mixture is cooled down a bit, until it's the temperature of a very warm cup of coffee, add the softened gelatin and stir until dissolved, then stir in the remaining 1/2 cup (125ml) of milk, espresso, vanilla, and salt.

Step 5

Transfer the mixture to a large measuring cup so it's easier to pour, and divide it into custard cups or glasses. Depending on the size of servings you want, choose whatever cups or glasses you'd like to use. Chill until firm, about 6 to 8 hours, or overnight.