Peel the pears, quarter them, remove the core and cut the fruit into cubes. Immediately mix with the juice of one lemon.
Boil white wine and sugar. Pour in the pear cubes and soften with the lid closed. Lift out of the broth and drain well. Grind finely with a hand blender. Cool.
Pour the yogurt into a large enough bowl. Stir in the pear puree. Whip the cream until stiff and stir in as well. Sugar to taste. Leave the cream to cool until serving.
Grate the chocolate or chop it as small as possible with a large kitchen knife.
Before serving, fold a good half of the chocolate into the pear cream and fill into glasses or dessert bowls. Sprinkle with the remaining chocolate.