Preheat the oven to 200C/180C Fan/Gas mark 6.
Cut the squash into half widthways and then lengthways, so you have four quarters. Remove and discard the seeds and put the squash into a baking tray, skin side down. Drizzle with 2 tablespoons of olive oil and the honey, thyme leaves and a pinch of salt.
Roast in the oven for 40 minutes to an hour, or until the squash is soft and the skin is starting to blister. Remove from the oven and allow to cool slightly before removing the skin and cutting the squash into cubes.
For the pickled red onions, combine the red wine vinegar, water, sugar and salt in a bowl to make a quick pickling liquid. Stir until the sugar and salt have dissolved.
Thinly slice the red onion and add to the bowl with the pickling liquid. Put in the fridge to marinate for at least 20 minutes.
Cut 5 or 6 thin slices from the sourdough and drizzle a little olive oil on each side of the bread. Add to a baking tray and put into the same oven as the butternut squash. Cook for about 8-10 minutes or until the bread is golden and crisp. Remove from the oven and allow to cool slightly.
Toast the hazelnuts in a dry frying pan for a few minutes until they become golden brown. Shake the pan regularly so they colour evenly. Remove from the pan and allow to cool slightly before roughly chopping.
Remove the onions from the pickling liquid and set aside. To make the salad dressing, add the Dijon mustard, lemon juice and zest, a pinch of salt and freshly ground black pepper to the pickling mixture and stir to combine. Add the 3 tbsp of olive oil and whisk to emulsify.
To serve, add your mixed salad leaves to a large serving bowl. Add the butternut squash, capers, pickled onions and toasted hazelnuts. Pour over the salad dressing (you might not need all of it) and mix the salad with tongs until everything is combined. Cut the Lypiatt cheese into thin slices and drape on top of the leaves. Roughly break up the toasted sourdough croutons into smaller pieces, scatter over the top of the salad and serve.