Heat oven to 160C/140C fan/gas 3. To make the dukkah, put the macadamias and hazelnuts on a baking tray and roast for 8 mins or until just golden. Leave to cool, then chop in a food processor and tip into a bowl. Roast the sesame, coriander, cumin and fennel seeds on a separate tray for 5 mins or until golden. Cool, then using a grinder or pestle and mortar, grind to a medium powder with the fenugreek, salt and hot smoked paprika, if using. Add to the ground nuts, mix thoroughly and set aside.
Increase oven to 200C/180C fan/ gas 6. Put the garlic, thyme, cream and soy or salt in a small pan and place over a medium heat to warm through. Remove and set aside.
Butter a 30 x 20cm ovenproof dish and layer up the vegetables. First put 2 layers of beetroot, then a layer of potato, a scattering of fennel, leek and ginger, and spoon over a little cream mixture. Repeat this process until you have used up all the vegetables and cream, finishing with a layer of beetroot. Press down on the gratin, then cover with foil and bake for 45 mins or until the vegetables are tender.
Remove foil from the gratin. Increase oven to 220C/200C fan/gas 7 and bake for a further 10 mins or until the top begins to brown. Remove gratin from the oven and let stand for about 10 mins.
Meanwhile, bring a small pan of water to the boil. Boil the eggs for 7 mins, then cool under cold running water, peel and set aside. Keep the pan of water as you will need this later to reheat the eggs.
To serve, reheat the peeled eggs in boiling water for 1-2 mins, the cut in half lengthways. Cut the beetroot gratin into 6 squares and put a piece on each of 6 plates. Scatter a handful of watercress over each, then carefully position 2 egg halves on top. Sprinkle a generous spoonful of dukkah over each half and drizzle over some extra virgin olive oil.