"...calls for a pack of raspberry jello..."
I was under the impression that the word 'jello' in USA means 'jam' in UK. (Coloured wobbly stuff made from fruit-flavoured gelatine)

We used to pinch a cube of Chivers jelly from the packet and chew it all the way to school. We fondly imagined our mum never noticed (of course she did!) That, together with desiccated coconut and a handful of illicit glace cherries made a delightful but naughty treat. In those days, mums' pantries had no end of home-baking stuff. Nothing was 'bought in'.