Melt the chocolate in short bursts in the microwave, or in a heatproof bowl set over a pan of simmering water ensuring the bowl doesn't touch the water. Leave to cool for a few seconds before mixing in a little of the yogurt.

Finely grate the zest from half the orange, then cut away the peel and pith, and chop the orange flesh. There is no need to cut away the membrane between the segments unless it is very tough.

Stir the remaining yogurt into the chocolate to combine, then the grated zest. Put the orange pieces in the base of two small serving glasses, then spoon the chocolate mix on top. Will keep chilled for up to three days. Scatter over a few mint leaves to serve.