Nougat parfait: Boil milk and vanilla pod. Add sugar, egg yolks and cinnamon and stir well. Add the boiling milk and stir the mixture until it has cooled down and is compact. Heat the nougat to about 50 °C (water bath or microwave). Carefully fold the egg mixture into the 900 g whipped cream using a whisk. In a second baking bowl, stir the 100 g whipped cream into the nougat. Next, gradually mix into the top cream. Finally, add the walnuts. Fill the parfait in a bomb or other give and put in the freezer in about 24 hours.
Plum sauce: Put the plums in boiling water until the skin can be removed. Remove the skin from the fruit, cut in half and remove the seeds.
Crush 200 g of the fruit and cut the remaining 600 g into quarters. Bring the sugar to a boil with the mashed fruit. Add the quartered fruit and simmer for a short time. The fruit must still have bite. Add the port wine and simmer for 8 hours. Before serving, season the fruit sauce with a few squeezes of lemon juice (depending on the acidity of the fruit). The ice cream bomb will tolerate a tart, fruity sauce.
To turn it out, dip the mold in lukewarm water for a few seconds up to the rim, turn it out onto a platter and serve with plum sauce. For decoration, the roasted walnuts are placed on top of the crest.