Preheat the oven to 200°C/gas mark 6. Cut the butternut squashes lengthways so you have 4 halves, and scoop out the seeds. Use 1 tbsp of oil to rub over the halves and season. Place them on a large baking tray cut side up and roast for 1 hour or until the flesh is tender.
Scoop out the flesh from each butternut squash, leaving a 1cm border. Roughly mash half of the butternut flesh and set aside, keeping the shells warm. Once cooled, you can keep the other half of the butternut flesh in the fridge for a few days for another meal. Set your oven to a medium grill.
Add 1 tbsp olive oil to a large frying pan and set over a medium/low flame. Add the sliced garlic while the oil is still cold and cook until the garlic starts to release its scent. Add the chilli and 1 tbsp sage and cook for a further 1 minute. Add the butterbeans and warm through for 5 minutes, roughly crushing with a potato masher. You still want there to be whole butterbeans. Add the saved butternut flesh and stir through, followed by 50g goat's cheese. Add 75ml warm water and stir through, seasoning well. Remove from the heat and keep warm.
In a medium frying pan, add the remaining oil and set over a medium heat. Add the crushed garlic and the whole sage leaves. Cook in the oil until the garlic starts to turn brown. Remove the garlic and sage from the pan and add the sourdough. Toss in the oil and cook for 2 minutes. Transfer the frying pan to the grill and cook for 3-4 minutes until the bread is golden brown and crispy. Remove from the grill.
Share the mash among the 4 butternut shells. Season the croutons and toss with the remaining chopped sage. Scatter them over the top of the butternut with the remaining goat's cheese and extra chilli flakes.