Roughly chop all but 4 of the pancetta slices. Heat the oil in a frying pan and fry both the chopped pancetta and the remaining 4 pancetta slices whole until crisp. Remove from the pan and drain on kitchen paper. Set aside.
Add the stock to a large saucepan with half the pesto. Bring to the boil, then add the pasta, frozen vegetables and fried chopped pancetta. Simmer with the lid on for 5 minutes until the veg and pasta are tender.
Divide between 4 bowls. Swirl a spoonful of the remaining pesto into each bowl, then top with a strip of crisp pancetta, a few basil leaves and a grinding of black pepper to serve.