Butternut squash soup with ricotta patties

1 medium butternut squash
3 tbsp olive oil, plus extra
4 small onions, chopped
2 sticks celery, chopped
25 g butter, plus extra
750 ml vegetable stock
A few whole sage leaves
For the ricotta patties
250 g ricotta
1 large egg yolk
3 tbsp grated pecorino cheese
3 tbsp plain flour
1 tbsp finely chopped sage
1
Preheat the oven to 200C/Gas6; peel and deseed the squash, cut three-quarters into chunks and season; roast for 35-40 minutes in a tin with half the oil; dice the remaining squash
2
Soften the onions and celery in the butter and remaining oil; puree the roast squash in a blender with half the stock; add to the onions and celery with all the stock and diced squash; simmer for 15 minutes
3
Combine the ingredients of the patties; fry in a mixture of butter and oil over low-medium heat for 2-3 minutes on each side; fry the whole sage leaves in butter
4
Serve the soup topped with the patties and frizzled sage leaves