In a large shallow dish, combine the coffee and Masala (or alternative), set aside.
Place cream in a large bowl and whip to soft peaks. Set aside.
Reserve 1 tablespoon of sugar, and place the remainder in a large glass bowl along with the egg yolks. Place about 5cm water into a saucepan and bring to the boil. Remove from heat and using a hand-held mixer, whisk on high speed until thick and very pale - about 4-6 minutes. Remove from heat and continue to whisk until cooled. Gently fold in mascarpone, followed by the whipped cream until just combined.
In a separate bowl, whisk egg whites to soft peaks, add reserved sugar and continue to whip to medium peaks. Gently fold egg whites into mascarpone mixture.
Dip the chocolate cookies in the cooled coffee mixture, allowing them to soften. Place a layer of cookies on the base of the dish. Spoon or pipe half the mascarpone mixture over, and repeat the process with remaining components. Chill for 2 hours or ideally, overnight.
Remove tiramisu. Sift over a generous coating of cocoa powder and serve.