Lemon cream filling: Place all ingredients except butter in a pot. Cook, stirring constantly, for 15–20 minutes until thickened (the constant stirring prevents the eggs from congealing). Remove pot from heat, add butter, and stir until butter dissolves in the mixture. Cool for 15 minutes. Strain the cream (a must!) and blend with a blender or an immersion blender, until cream is smooth and velvety.
Make dolce de leche layer:
Whip heavy cream with sugar until stiff. Lower mixer speed, and with mixer running slowly, add remaining mousse ingredients.
Assembly:
Pour Passion fruit layer into individual silicone molds or a round pan and freeze for 1 hour.
Pour on top the dolce de leche layer and freeze for 4 hours, release from pan.
For another layer take a quarter of dolce de lece layer and add to it 12 container whipping cream in order to make it lighter,pour that layer between passion fruit layer and dolce de leche layer.