Heat the oven to 220C/200C fan/ gas 7. Prick the potatoes all over with a fork, rub over the oil and season with salt. Put the potatoes directly on the oven rack and bake for 1 hr until the skin is crisp and golden, and the potatoes are cooked. Leave until cool enough to handle, about 15 mins. Meanwhile, cook the broccoli in a pan of boiling water for 3-4 mins until just tender. Drain.

Cut the baked potatoes in half lengthways and scoop the flesh into a bowl, leaving a border. Put the skins on a baking tray. Mash the potato flesh, then stir in the butter, two-thirds of the cheese, and the broccoli. Season. Spoon the filling into the potato skins. Top with the rest of the cheese and bake for 15-20 mins until golden.