Scrub potatoes under running water; dry and rub the skin of each with the oil and a little salt.
Pierce the skin of each, in three or four places, with the tines of a fork.
Place the potatoes in the oven, and roast for 45 minutes to an hour, depending on the size of the potatoes, until they offer no resistance when a knife is inserted in their centers.
While the potatoes are baking, put the cauliflower into a saucepan, set over medium-high heat, and add the milk and bay leaves.
Heat until almost boiling, then reduce flame to low, and simmer until tender; approximately 20 minutes.
When the potatoes are done, remove from the oven, slice them open down the middle (be careful not to cut all the way through) and use a spoon to scrape out their flesh into a bowl.
Add the salt, pepper, scallions, butter, the cauliflower and a healthy splash of the milk, and mash to combine.
Spoon the mixture back into the empty jackets, place on a baking sheet and shower with cheese.
Return to the oven, for approximately 15 minutes, until the cheese is melted and golden.
Notes
This is delicious, but very rich. Try serving it along with pork schnitzel and a salad or serve the potato as the main dish with a side of green salad.