Preheat the oven to 200°C (180°C fan) (390°F).
Cut the butternut squash lengthways, scoop out the seeds, and slice into 2cm thick half-moons.
Cut the onion into wedges.
Place the squash, onion, and smashed garlic in a large roasting tin. Drizzle with 2 Tbsps of olive oil, season with salt and pepper, and toss to coat.
Bake in the middle of the oven for 15 minutes.
Tuck the apple wedges between the vegetables, brush lightly with oil, and roast for another 10 minutes.
Meanwhile, season the pork fillet with salt and pepper, then rub with 1 Tbsp of olive oil.
Heat a griddle pan over medium-high heat and sear the pork on all sides until lightly browned.
Cut the sage leaves into thin strips and toss them with a little olive oil.
Place the seared pork on top of the roasted vegetables, scatter over the sage and ground ginger, and roast for 15 minutes, or until the pork is just tender.
Transfer the pork to a plate and let it rest for 5 minutes before slicing.
Serve with the roasted vegetables, crispy sage and apple.