In a saucepan, heat the raspberry purée with half the sugar.
In a bowl, combine the egg yolks with the remaining sugar with a whisk. Gradually add the warm raspberry purée, whisking constantly. Pour the mixture back into the saucepan and cook gently for about 1 minute, stirring continuously. Strain through a sieve over the chocolate. Let stand for 1 minute, without stirring.
With a whisk, stir until smooth. Divide among six espresso cups or 4 verrines. Cover and refrigerate for 4 hours or overnight.
Notes
For about 250 ml (1 cup) seedless raspberry puree, puree 1 liter (4 cups) thawed frozen raspberries until smooth, then strain the puree through a fine sieve.