Start by rinsing the lemons thoroughly under cold water. Cut each lemon in half and scoop out the flesh, creating lemon shells.

Squeeze the juice from the lemon halves into a bowl, using a fine mesh strainer to catch seeds or pulp.

In a saucepan, combine heavy cream, granulated sugar, and lemon zest. Heat gently over medium-low for about 5 minutes, without boiling.

Remove from heat and stir in the freshly squeezed lemon juice and vanilla extract.

Strain the mixture through a sieve if desired. Allow to cool for 10 minutes, then pour into lemon shells and refrigerate for 1-2 hours until set.

Before serving, sprinkle sugar over the tops of the filled lemon shells and caramelize with a kitchen torch for a crunchy layer.