Click off and discard only the tatty outer leaves from the cauliflower, then cut it into quarters.
Blanch in a pan of boiling water for 5 minutes, then drain.
Meanwhile, peel the onion and chop into sixths.
Halve the chicken thighs.
In a 28cm non-stick ovenproof frying pan on a medium-high heat, fry the chicken and onion with 1 tablespoon of olive oil, a pinch of sea salt and lots of black pepper until lightly golden, stirring occasionally.
Add the cauliflower to the pan.
Cook and turn for 5 minutes, then push it all to one side of the pan and add the pancetta to crisp up.
Now add the tomatoes, mustard, honey and 1 tablespoon of red wine vinegar, and mix well.
When it’s looking really golden, roll the pastry out a little to fit the pan and place it over the top, using a wooden spoon to push it right into the edges.
Bake for 25 minutes at the bottom of the oven, or until golden and puffed up.
Using oven gloves, pop a large plate over the pan and confidently but very carefully turn out and serve.
