To make the dough: In a large bowl combine the semolina, sugar and baking soda. Using your hands mix together to infuse. Add the 150 ml of the cold sugar syrup, and mix well with the tips of your finger allowing the sugar syrup to penetrate the semolina dough. Add the powdered milk (if used).
Add the water (150ml) in a gradual fashion and mix using your hands until you obtain a thin dropping consistency but not liquid dough.
Grease a round baking tray ( 38 cm /15 inches ) with both tahini/ sugar syrup and ghee, make sure to grease the bottom and sides equally. Transfer the dough to the greased tin and spread it in a leveled single layer. Shake the tin a bit to help even out the batter. The depth of the batter should be 1 1/2 cm/ 1/2 inch deep, this will give a moderatethick namoura result, note that the batter will rise a bit while baking.
Cover with clingfilm and leave it for a minimum of 8 hours to a maximum of 12. This well help the semolina grains to swell. (This is how it is done at pastry shops in Beirut).
Preheat the oven to 200°C/400°F.
With a serrated knife, score the dough into equal squares or diamonds.
Add your favorite nuts in easch square. It could be blanched sliced almonds, pine nuts or cashews.
Bake the namoura in the lower rack of the oven for 20 minutes. At this stage you will notice your namoura started to put on some color. Remove from the oven and one more time, using a serrated knife, cut all the way through the markes you have made earlier; add the ghee equally atop of the namoura.
Place the oven rack in the center position and return your namoura for further 15 minutes or until the top is golden brown.
While the namoura is baking, prepare the sugar syrup: Place the sugar and water in a pot over high heat. Bring to a boil and stir to dissolve the sugar. Add the lemon juice (this will prevent the sugar syrup from crystallizing), keep it boiling over high heat for 2 minutes. Add the orange blossom, remove from heat and keep it hot.
Once the namoura surface and bottom is deep brown, remove from the oven, and rapidly, pour the piping hot sugar syrup all over the namoura. The namoura will soak up the sugar syrup in a few minutes.
Set aside for 3 to 4 hours before, With a pie server spatula, transfer the namoura squares to a serving plate.