Heat the oven to 220C (200C fan)/425F/gas 7. Tip the yoghurt into a muslin or clean cloth set over a sieve, bring the corners of the cloth together and gently twist so the yoghurt is completely encased in a ball. Fasten with string (or a rubber band) and tie to a cupboard handle with a bowl underneath to catch the liquid.
Meanwhile, tip the sliced carrots into a large roasting tin (they should almost sit in one layer), then toss through the garlic, za’atar, olive oil and salt. Cover tightly with tinfoil and roast for 20 minutes.
Remove the foil, drizzle over the maple syrup, then return to the oven for a final 10 minutes. At the same time, pop the pistachios on a baking tray, and put them on a lower shelf of the oven to toast (if your oven is fierce, rescue them after six to eight minutes). Roughly chop the toasted pistachios into chunky pieces.
When you want to serve, warm through the carrots for 10 minutes in the oven, if need be. Untwist the cloth, spread the labneh over a platter and arrange the carrots on top. Squeeze over the lemon juice, scatter over the pistachios and mint leaves, if using, and serve warm or at room temp.
