Parfait: Heat 150ml whipping cream, sugar and egg yolks in a double boiler for about 10 minutes, stirring constantly until a thick cream forms. Do not boil!
Transfer cream into a bowl and mix in rum, spices and salt. Chill for 45 minutes.
Brittle Filling: Preheat oven to 180 degrees C. Line baking tray with a well greased sheet of foil.
Mix walnuts, brittle, brown sugar, salt and butter and spread in a thin layer onto prepared baking tray. Bake for 15 minutes. Allow to cool, then chop up.
To Assemble Beat the remaining cream and fold into cooled pumpkin cream. Chill for at least 4 hours.
Line a shallow large bowl with cling wrap and add 1/3 of the pumpkin cream. Sprinkle with 1/3 of the brittle. Repeat twice. Cover tightly with foil and chill overnight. Remove from fridge 30 minutes before serving out and gently turn upside down.