Combine chocolate and butter in a heavy-bottomed sauce pan over extra low heat. If your stove does not have an extra low or melting option, use a double boiler.

In a small glass or ceramic bowl, whisk together plain and raspberry yoghurts with corn starch. Add yoghurt mixture to the melting chocolate, along with the preserves, lemon juice and salt. Mix well. Cook for about 15 minutes, whisking occasionally. Serve in a fondue pot with pound cake and fresh fruit for dipping

Makes 12 servings (about 3¼ cups).