A little in advance: in a bowl, let the grapes macerate in the rum.
Preheat the oven to 180°.
Beat the sugar and the eggs then add the cottage cheese and the flour. Mix to obtain a homogeneous dough. Flavour with a few drops of lemon juice and add the grapes. Pour the mixture into a buttered mould.
Bake in the oven for approx. 35/40 min., observing the coloring at the end of the firing process.
Allow to cool and serve.