Place evaporated milk, cream, vanilla extract, yolks and sugar in the blender until well combined.
Bring the mixture to simmer over low heat in a small sauce pan. Stir often until custard thickens, about 7 minutes (do not let it boil). Strain sauce into a bowl. Cover and place in the fridge until ready to use.
To make rum syrup:
In a small pot, combine the water and sugar. Cook over medium heat until the sugar dissolves. Remove from the heat and stir in the rum and prunes.
Using a serrated style knife, cut the cake in half horizontally. Place 1 layer on a plate. Drizzle ½ of the rum syrup over the top, then drizzle half of the creme anglaise and top with half of the prunes.
Top with another cake layer and repeat with the rest of syrup, creme anglaise and prunes.
Serve immediately, or cover with a cake cover and refrigerate until ready to serve.