Halve the vanilla pod lengthwise and scrape out the pulp with the back of a knife. Bring 300 ml milk to the boil. Add ginger, cayenne pepper, chai tea powder, vanilla pulp and cinnamon stick, mix and leave to stand for about 5 minutes. Pour tea through a sieve and puree with vanilla ice cream.
Heat 100 ml milk and whip until frothy with a hand blender. Pour milk shake into 4 glasses, add milk foam and dust with cinnamon.