Chai Spice Blend
For spice blend, grind cinnamon stick in a spice mill (or coffee grinder used just for spices) or with a mortar and pestle. Add remaining spices and grind into a powder.
For filling, whip cream to medium peaks, stir in vanilla and chill. Beat mascarpone and cream cheese with sugar on low speed until smooth. Stir in coffee liqueur and Chai Spice blend. Fold in whipped cream and chill until ready to assemble.
To assemble, heat sugar, water and Chai Spice blend until sugar dissolves, stir in vanilla and remove from heat.
Dip wafer cookies in syrup briefly and line the bottom of an 8-cup trifle dish or serving dish. Spoon 1/4 of the chai filling over cookies and place another layer of soaked cookies over mousse. Repeat layering with mousse and cookies, finishing with the mousse. Chill for at least 4 hours before serving.
To serve, whip cream with sugar and vanilla and dollop on top of tiramisu. Dust lightly with cocoa powder and serve.