Heat the milk in a small bowl till it's warm, but not hot and you can comfortably dip a finger in. Stir in the yeast and sugar, cover and set aside to let it become frothy, about 5 minutes.
In the bowl of a stand mixer fitted with the dough hook, or in a large mixing bowl, combine the yeast mixture and olive oil. Mix for a few seconds.
Add the flour, salt and seasoning and mix till a shaggy dough comes together. If using a mixer, let it run on medium-low speed for 3 to 4 minutes until you have a smooth, barely sticky dough. Knead it briefly and gently by hand to smoothen, then poke a finger lightly into it. If the dough slowly bounces back, it's ready to rise. If not, knead a little bit more till it does. If make the dough by hand, mix and knead the dough on a lightly floured counter for about 5 to 6 minutes, until smooth.
Lightly oil the bowl you just used, then place the dough in it. Cover tightly with clingfilm and set aside to rise in a warm place for 1 to 2 hours, until doubled. Or preheat your oven to its lowest temperature (mine is 100C) for two minutes, turn it off, and place the bowl inside to speed up the rise in cold weather.
While the dough is rising, fry the sliced onions in one tablespoon olive oil until lightly browned. Set aside to cool a bit.
Lightly grease a 9x13 inch pan or if you don't have it, do what I did and use two pans: an 8 inch square pan which will fit 9 rolls and another smaller dish, about 8x4 inches which will fit 3 rolls.
When the dough has doubled, punch it down to release the air, then turn it out onto a lightly floured counter or large silicone mat. Roll it out into a roughly 12x16 inch rectangle, using your fingertips to even out the sides. Spread the second tablespoon of olive oil over the dough.
Spread the cheese over the dough, then sprinkle the cooked onions all over it.
With the shorter end facing you, roll the dough up tightly and place it seam side down on the mat or counter. Slice using a sharp knife into 12 equal rolls. Place each one in the prepared pan(s), leaving about an inch gap between each for the second rise. Cover tightly with clingfilm and leave to rise again for about 1 hour until puffed and doubled. See photos below.
Preheat the oven to 175 C. Remove the clingfilm from the pan and sprinkle on the remaining 1/2 cup of cheese over the top of the rolls. Bake for 30 to 35 minutes (if you bake all 12 at once, the baking time might increase by about 10 minutes) or until lightly browned, and the cheese is golden and bubbling lightly around the sides.
Allow the rolls to stand for 10 minutes, then using a sharp knife, cut each one out and eat immediately! Store at room temperature for a day and then in the fridge for 3 to 4 days although they're best eaten fresh. Happy baking!