Whip the heavy cream in a cold bowl to soft peaks, the point where a lifted whisk leaves a peak that folds over on itself.
In a second bowl, stir the Greek yogurt, honey and vanilla together until smooth.
Fold a third of the whipped cream into the yogurt to loosen it, then fold in the rest gently until no white streaks remain. Fold, do not stir, so the air stays in and the fluff stays light.
Fold in most of the drained mandarin segments, holding a few back. Drain them well first, since carried juice thins the fluff.
Spoon into a serving dish or individual cups, scatter the reserved segments on top, and chill at least 1 hour so it sets and the flavours settle.