Then put the water, raspberries and sugar into a saucepan and bring to a boil whilst swilling around to allow the colour to come out of the raspberries.
Mashing them will release a load of pips, but you can gently press them with the back of a fork to get more pink juice into the mix.ter to soften them.the raspberries.
Now take the gelatin out of the water and whisk it into the hot raspberry syrup until totally dissolved. Add the elderflower and then pour in the prosecco, but slowly to avoid it fizzing up!.