1: Trim 1 cauliflower, only keeping the best of the leaves around the base and cutting these back to half their length.
2: Put a small dessert ring in the bottom of a large pan of salted boiling water.
3: Sit the cauliflower on the ring, head downwards. It doesn't matter if the end is slighty above the water level. Cook until barely tender.
4: Take out of the pan and drain, still head downwards, in a colander.
5: Preheat the oven to 360°F (180°C). Put 30 g butter in a ramekin and melt (in the microwave, for example). Add 3 tablespoons olive oil and mix well.
6: Sit the cauliflower right way up on a sheet of cooking parchment laid on a baking sheet. Use a brush to coat the cauliflower thoroughly all over with the butter-oil mixture, including the leaves. Put in the oven.
7: Take out the baking sheet 2 or 3 times during cooking and brush the cauliflower again with the butter+oil.
8: Take the cauliflower out of the oven when it is nicely browned (this will take an hour and a half to 2 hours) and the surrounding leaves are charred and crispy, almost burnt.
9: To serve, place the cauliflower in the centre of the table for everyone to help themselves to well-roasted morsels...
10: ...and dip them in the green sauce before eating. You'll love this!