Ahead of time, make the maple-glazed walnuts: preheat the oven to 200°C, fan 180°C, gas 6 and coat the walnuts in the maple syrup and 1 teaspoon of olive oil. Season with salt and spread out on a lined baking tray. Roast for 8-10 minutes until golden and smelling toasty. Set aside to cool. They will keep crisp for up to 3 days in an airtight container.
Add the halved Brussels sprouts to a large pan of salted boiling water and cook until just tender, 4-5 minutes. Drain well. See ‘Get ahead’, above, if preparing in advance.
Meanwhile, add the pancetta to a large cold frying pan and fry over a medium heat for 8-10 minutes, stirring occasionally; the fat will render out, then continue to cook the pancetta until crisp.
Add the sprouts to the pan, along with the glazed walnuts. Season and stir-fry for 3-5 minutes until piping hot. Tip into a warmed serving dish.
