1. Preheat your convection oven to 180°C. Grease a spring form pan (26 cm Ø) with butter. Wash the courgettes, peel the carrots. Cut both lengthwise into millimetre-thick slices using a vegetable slicer or a slicing machine. Roll out the puff pastry and cover the pan with it. Cut off the excess around the edges and attach as a crust. Use a fork to pierce the bottom several times.
2. Grate the Kashkaval medium-fine. Mix together the yoghurt, eggs and ¼ tsp nutmeg, 1 tsp salt and ½ tsp pepper with a hand mixer. Pour the yoghurt cream into the pastry. Spread the mixture evenly and sprinkle with the cheese.
3. Roll the carrot and zucchini strips alternately with your hands. Place the roll in the middle of the pan and continue in a circular direction, all the way around to the edge. When the mould is filled or the strips have run out, loosen the strips at the outer edge slightly with your hands. Sprinkle the goat cheese and thyme leaves over everything. In the hot oven, bake for 45-50 minutes on the medium rack until the edge is golden brown.
4. Serve the tart warm or cold as desired.