Bloom the gelatin: In a small bowl, sprinkle gelatin over 3 tablespoons cold water. Let stand 5 minutes until spongy.
Warm the cream: In a saucepan, combine cream, milk, sugar, cardamom, saffron, and salt.
Warm over medium heat until steaming and sugar dissolves. Do not boil.
Add gelatin: Remove from heat. Stir in the bloomed gelatin until fully dissolved.
Add rose water if using. Taste and adjust sweetness.
Set the base: Pour into 4–6 ramekins or glasses. Cool 15 minutes, then chill at least 4 hours, or until set with a slight wobble.
Make the mango coulis: Blend mango, lime juice, sugar or honey, and a pinch of salt until smooth.
Adjust acidity and sweetness. Chill.
Prepare the crunch: Crush biscuits into coarse crumbs. Toss with melted ghee, sugar, and cardamom.
Toast in a dry skillet over low heat for 2–3 minutes until fragrant. Cool.
Assemble: Spoon a thin layer of mango coulis over the set cream. Top with a sprinkle of biscuit crunch and chopped pistachios.
Add rose petals if you like.
Serve: Chill 10 minutes to set the coulis slightly. Serve cold with extra coulis on the side.