Preheat oven to 200C. Peel and chop the butternut squash into 1-2cm pieces. Pick the leaves from the rosemary and finely chop.

Add the squash to a roasting tray with 1 tbsp olive oil and the rosemary. Toss together with sea salt and black pepper and roast in the oven for 15-20 minutes. Once roasted, remove from the oven and set aside.

While the butternut squash is roasting, start on the prep for the filling. Roughly chop the sage leaves. Finely dice the onion and garlic.

Finely chop the chestnut mushrooms. Roughly chop the cooked chestnuts and the parsley.

Heat 1 tbsp olive oil in a frying pan over heading heat. Add in the baby spinach and allow to wilt down with some salt and pepper. Then remove onto a plate lined with kitchen paper to cool and drain.

Return the frying pan to a medium heat and add in the butter. Once the butter is bubbling add the sage and allow to fry for 30 seconds until crisp. Add in the onion and allow to cook for 5-6 minutes until translucent and soft before adding the garlic and cooking for another minute.

Next add in the mushrooms and chestnuts and allow to fry for 10 minutes on a medium high heat until most of the moisture is gone. Season with salt and plenty of black pepper. Add the breadcrumbs and allow to toast in the pan for 3-4 minutes.

Add the mushroom mix and chopped parsley to a bowl with the butternut squash and mix well to combine.

Once the spinach has cooled, squeeze between the kitchen paper to remove excess liquid. Arrange the spinach in a rectangle on to ⅓ of the puff pastry to one side, leaving a 3cm gap around the edge for the trim. Scoop the butternut squash mixture on top of the spinach and form into a loaf shape.

Brush the edges of the puff pastry with a beaten egg and fold the larger side of the puff pastry over the filling. Leave a 3cm trim all the way around and press down with your fingers to seal. Crimp the pastry any way you like.