Beat milk and sugar with the chilled beaters of electric whisk until light and fluffy.
Place in refrigerator to chill.
Stir jelly into the hot water until jelly crystals have completely dissolved.
Stir in granadilla pulp. Allow to cool. Refrigerate jelly until it becomes thick and wobbly but not set.
Beat chilled evaporated milk again, gradually adding jelly and granadilla pulp in a thin stream until all is well incorporated and fluffy.
You may chill again and then beat until it reaches its maximum volume.
Layer biscuits and pour over mixture.
My mother used to do this in a fruit salad bowl by adding a layer of crushed biscuits, followed by flummery mix. Then another layer topped by more flummery and so on.
Crumble a few crushed biscuits over the top of the last bit of flummery and refrigerate until set.
Another variation: You may layer the whole tennis biscuits on the base of a square 20 x 20 pan (no crushing) add half the mixture, second layer of whole tennis biscuits and finish with a final layer of mixture. – Enjoy!