Infuse the Cream: Gently heat the cream in a small saucepan – don’t let it boil. Add the Assam tea and saffron, cover, and steep for 20 minutes. Strain and let cool completely.
Make the Crust: Mix the crushed Biscoff biscuits with melted butter and a pinch of salt. Press firmly into a greased springform pan (18–20 cm / 7–8 inch).
Pre-bake at 160 °C (320 °F) for 6–8 minutes, then let cool.
Prepare the Filling: Beat the cream cheese until smooth. Add coconut sugar and beat until creamy.
Mix in yogurt, sour cream, vanilla, the cooled chai cream, spices, and flour. Stir just until smooth – don’t overmix.
Bake: Place a shallow oven-safe dish of hot water on the bottom rack of the oven (for steam).
Pour the filling into the crust and bake at 150 °C (300 °F) for about 45 minutes, until the center still has a slight wobble.
Turn off the oven, crack the door slightly, and let rest inside for 10 minutes.
Remove, cool completely, and chill for at least 6 hours, ideally overnight. Once fully chilled, the cheesecake keeps well in the fridge for up to 4 days. Cover it loosely to avoid condensation on the surface. The flavors deepen a little by the next day – even better if you make it ahead.
Make the Topping: Mix butter, honey, cinnamon, and salt until smooth.
Spoon over the cheesecake before serving or serve on the side.