Separate the eggs if necessary and zest the lemon.
Measure out milk, sugar, and vanilla sugar.
Mix the Cream
In a saucepan, combine milk, lemon zest, and both sugars.
Heat gently over medium heat until warm, but do not boil.
Add the Eggs
Beat the eggs lightly in a bowl.
Slowly add a small amount of the warm milk mixture into the eggs while whisking to prevent curdling.
Pour the egg mixture back into the saucepan.
Cook the Lemon Cream
