Whisk together 4 whole eggs, 4 egg yolks (reserve remaining whites), and 1 cup sugar in a 4-qt.

saucepan.

Add kosher salt, lemon juice, and zest; stir until smooth.

Place the saucepan over medium heat and cook, stirring continuously, until the mixture thickens to the consistency of loose pudding, about 10 minutes.

Pour through a fine strainer into a large bowl and chill in the refrigerator.

In a separate bowl, whisk the reserved egg whites with the remaining ¼ cup of sugar until stiff peaks form.

Gently fold the egg whites into the chilled lemon curd mixture.

In another bowl, whisk the heavy cream and vanilla extract until stiff peaks form.

Fold the whipped cream into the lemon curd mixture until fully combined.

Spoon the lemon mousse into serving cups and chill in the refrigerator before serving.