Mango Shrikhand with Pistachio Crumble

Name: Mango Shrikhand with Pistachio Crumble
Ingredients: 4 cups whole milk plain Greek yogurt; 1/2 teaspoon saffron threads; 2 cups unsweetened mango pulp (canned is easiest); 4 green cardamom pods, seeds only, crushed into a powder or 1 teaspoon ground cardamom; 1/4 cup granulated sugar, plus more to taste; 1/2 cup raw shelled pistachios; 1/2 cup crushed digestive biscuits or graham crackers; 4 tablespoons unsalted butter, melted; 2 tablespoons dark brown sugar; 1/4 teaspoon kosher salt