This frozen lime torte is wonderful on a hot day. It's perfect for summer or any holiday you celebrate with fresh berries.
Combine sugar, milk, egg yolks, lime juice and lime zest in a bowl. Place the bowl over a saucepan of simmering water (do not allow bottom of bowl to touch the water). Whisk constantly until candy thermometer reaches 170 degrees F about 5 minutes. Remove bowl from over water. Add white chocolate and whisk until melted and smooth. Freeze lime mixture until cold and thickened, whisking occasionally, about 45 minutes.
Bring blackberries, raspberry juice, and 1/2 cup sugar to a boil in heavy saucepan, stirring frequently. Cool slightly. Puree mixture in a food processor. Strain through sieve set over a bowl, pressing on solids. Chill until cold. Can be made 1 day ahead.