In a heavy pan, heat milk and sugar over medium heat, stirring frequently so it doesn’t scorch. Cook until it reduces by half (around 15–20 minutes).
Stir in saffron, cardamom, and any other aromatics you like.
Mix a little cornstarch with some of the remaining milk to create a slurry, then add it into the pan. Continue cooking over low heat until thickened, about 15 minutes.
Remove from the heat and immediately add chopped white chocolate, letting it melt before whisking smooth.
Stir in bloomed gelatin while the mixture is still warm. Leave it to cool to room temperature.
Whip the cream to medium peaks (soft but stable), then fold it gradually into the cooled kulfi base in 2–3 additions, using a spatula to keep the mixture airy. Avoid overmixing to preserve the mousse’s light texture.