1.Heat the grill to its highest setting.
2.Peel and halve the butternut squash and scoop out the seeds. Lay each half flat and cut it into slices about 5mm thick. Blanch the slices in boiling salted water for about 2 minutes then drain the squash well on a paper towel.
3.Mix the pumpkinseed oil and half of the balsamic vinegar together. Lay the butternut squash slices flat onto a baking tray and brush the slices sparingly with the pumpkinseed oil and balsamic dressing. Reserve the remaining dressing. Season the butternut squash slices well with salt and pepper.
4.Place the butternut squash under the grill for 6-8 minutes or until well browned and just starting to caramelise around the edges. Set aside and allow to cool.
5.To make the dressing, mix the other half of the balsamic vinegar with salt, pepper and a good pinch of sugar and add 1-2 tbsp water. Add this to the remaining pumpkinseed oil and balsamic mixture, add the vegetable oil and mix well.
6.Add the mi-cuit tomatoes and watercress to the balsamic dressing and toss together. Divide between four large plates. Arrange the butternut squash on top of the tomatoes and watercress.
7.Cut the parma ham into strips and scrunch between the butternut squash. Scatter over the toasted pumpkin seeds and the parmesan cheese shavings and serve.