Preheat the broiler. Place the zucchini on a baking sheet lined with aluminum foil and broil for about 45 minutes, turning once or twice during the cooking, until the skin crisps and browns nicely. Remove from the oven and, once cool enough to handle, peel off the zucchini skin and discard it. Set the flesh aside in a colander, and mash around with a fork until it's loosely pureed. Allow to drain for 10-20 minutes.
Meanwhile, in a small sauté pan, melt the butter with the pine nuts over medium-low heat and cook, stirring often, for 3 to 4 minutes, until the nuts turn golden brown. Transfer to a small bowl. Stir in the chile flakes and lemon juice and set aside.
Using the same pan you just used for the pine nuts, combine the yoghurt with the Roquefort and egg. Heat very gently for about 3 minutes, stirring often (otherwise the egg will cook, and you'll get a lumpy mass). You want the yoghurt to heat through but not quite reach the simmering point.
To serve, put the zucchini in a bowl and add the garlic, a scant 1/2 teaspoon salt, and a good grind of black pepper. Mash everything together with a fork and then spread the mixture out on a serving platter. Spoon the yogurt sauce on top, followed by the pine nuts and their butter sauce. Finish with a sprinkle of za’atar and serve right away.
Best consumed warm right after it's made, but it'll keep in a container in the fridge for several days.