Reserve 12 raspberries for decoration and place the rest in a food processor with a good squeeze of lemon juice.
Blitz to a puree, then push through a sieve to remove the seeds. Add icing sugar to taste, leaving the fruit slightly on the tart side, then set aside.
Place the egg yolks and caster sugar in a large, heatproof bowl. Beat in the sherry and wine, using a balloon whisk.
Place over a pan of simmering water and heat gently, whisking continuously until the mixture is very light but holds its shape. When it is the consistency of semi-melted ice cream, take it off the heat and continue to whisk over a bowl of iced water until cool - this prevents it from splitting.
Fold the yoghurt into the mixture. Drizzle in the raspberry puree and gently swirl to create a ripple effect. Spoon into stemmed serving glasses, decorate with the reserved raspberries and serve with wafer thin biscuits, if you like.
Type the ingredients you want to use, then click Go. For better results you can use quotation marks around phrases (e.g. "chicken breast"). Alternatively you can search by chef, programme, cuisine, diet, or dish (e.g. Lasagne).