Put the cream, yoghurt, powdered sugar, lemon and vanilla in a container. Beat with the mixer until stiff. Chill for at least 3 hours.
The yoghurt leaves a little liquid when it cools, so mix it up again if necessary. Roughly chop the nuts and roast them in the pan without fat. Let cool down.
When serving, form cams with two tablespoons. Garnish with the walnuts and honey.