Chill a mixing bowl and beaters in the freezer for 10 minutes.
Blend fresh mango until smooth; strain for silky pulp.
Whip the mango cream
Beat cold heavy cream in the chilled bowl until soft peaks form, 2 to 3 minutes.
Add mango pulp, sugar or jaggery, cardamom, and yogurt. Beat until thick, pale orange, and stiff peaks form, 2 to 4 minutes.
Make the lassi base
Whisk yogurt, cold milk, honey, salt, and cardamom until smooth and pourable.
Taste and adjust sweetness.
Layer and serve
Add ice cubes to four tall glasses.
Pour lassi base halfway up each glass.
Spoon whipped mango cream over the back of a spoon to layer on top.
Garnish with pistachios, saffron, and rose water if using. Serve immediately.
Notes
Cold bowl, beaters, and cream are essential for a tall foam.Simmer and cool thin mango pulp before whipping so the cream layer stays stable.Lassi base can be made up to 4 hours ahead; whip cream and layer just before serving.Best enjoyed within 30 minutes; foam softens if held too long.