Zest two fresh lemons and juice them to get about ½ cup of lemon juice. Gather heavy cream, sugar, and vanilla extract.

Combine heavy cream and granulated sugar in a saucepan over medium heat, stirring until sugar dissolves and mixture simmers, about 5–7 minutes.

Remove from heat and stir in lemon zest, lemon juice, and vanilla extract if using. Mix until smooth.

Let the mixture cool at room temperature for about 10-15 minutes to prevent condensation.

Pour the mixture into serving cups, cover with plastic wrap, and chill for at least 4 hours or overnight.

Garnish with fresh berries or lemon zest before serving.