Panettone Dressing Squares

Peel and halve the shallots (or peel and quarter the onions) and quarter and core the apples, and roughly cut up the pancetta (or bacon). Drop the shallot or onion and the apple pieces into the bowl of a food processor along with the celery stalks, snapped in half, and the sage leaves, and process in a short burst to start the chopping, before adding the roughly cut pancetta (or bacon), and then blitz at full speed until finely chopped. Don't worry about the mixture's wetness; mush is what I expect. You can chop everything by hand, though; in which case, don't expect to get everything as ground up as it would in the processor. Anything goes.
Heat the garlic-flavored oil in a wide, heavy frying pan and fry this mixture, stirring every now and again, for 10–15 minutes, until the vegetables et al. have softened. Remove the fried mixture to a large bowl, crumble in the chestnuts, grate in the lemon zest and squeeze in the juice, then tear and crumble in the panettone, and—I use my hands for this—combine everything into a squidgy, fragrant paste. (If you're making this in advance, leave it to cool at this stage, then cover and transfer to the refrigerator where it can stand for up to 2 days.)
When you are ready to cook this, preheat the oven to 400°F and let the dressing come to room temperature. Uncover the bowl, beat the eggs and mix them in, then spread the mixture into a foil pan or lightly greased ovenproof dish, and bake for 25–30 minutes, until the edges brown and begin to come away from the pan or dish and a cake tester comes out clean.
For appetizers, let the pan cool for 30 minutes and then cut into 48 little bite-sized squares—or into 24 larger pieces to accompany roasted meat, if you'd prefer.