How to Make It
In a medium saucepan, combine 1 cup of the verjus with the sugar and bring to a boil. Cook over moderate heat, stirring occasionally, until reduced by one-third, about 10 minutes. Add the cranberries and cook until softened, gently smashing the cranberries against the side of the pan, about 15 minutes.
Meanwhile, in another medium saucepan, combine the pears with the quinces and remaining 2/3 cup of verjus and bring to a boil. Cover and cook over moderately low heat until the pears are softened, about 20 minutes.
In a heatproof bowl, combine the cranberry sauce with the pears, quinces and grappa. Refrigerate until chilled.