Prepare 6 glasses: Place them in a muffin tin so they are stable when tilted.
In a small bowl, soak the gelatin with the milk. Reserve.
In a saucepan, bring the cream, sugar, and vanilla (seeds and pod) to a boil.
Remove from heat and let infuse for 5 minutes.
Strain the infusion through a fine sieve to remove the vanilla pod and saffron.
Add the gelatin that has been previously melted for 20 seconds in the microwave and mix well.
Incorporate the yogurt with a whisk and pour into the glasses.
Let set in the refrigerator for at least 4 hours.
Passion curd:
Cut the passion fruits in half and extract the pulp and seeds.
Put everything in a saucepan with the lemon juice and bring to a boil.
In a bowl, whisk the eggs with the sugar, then, while mixing, add the passion fruit and lemon juice mixture.
Return everything to the saucepan, then add the agar-agar and bring to a boil without stopping mixing for 1 minute,
Remove from heat, then add the butter. Mix until the butter is well incorporated.

Pour the passion curd over the panna cotta, to a thickness of 1/4 inch (5 mm) and refrigerate until completely set (about 2 hours).