Crumble the ciabatta into small pieces and spread out on a foil-lined grill rack. Scatter with the pine nuts and grill lightly until toasted.
Peel the marrow and cut across into 4 even-sized lengths, trimming off the ends. Using a dessertspoon, scoop out the seeds, leaving a small base in each, to make cups.
Melt the butter with 2 tablespoons of the oil in a small roasting pan and gently fry the pancetta for about 5 minutes until beginning to crisp and colour. Add the garlic, chilli and paprika and cook for a further 1 minute. Drain to a large bowl, leaving a little of the spicy oil in the pan.
Off the heat, put the marrow cups in the pan, turning them in the oil. Place upright and brush the centres with more of the spicy oil in the pan. Season with salt and bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 25 minutes or until tender.
Toss the pine nuts and ciabatta with the pancetta mixture and herbs and divide between the cups. Drizzle with the remaining oil and return to the oven for a further 15 minutes.