In a large bowl or sheet pan place the cubed squash and drizzle 1 tablespoon of olive oil, the salt and pepper and toss.
In a large stock pot or dutch oven, heat 2 tablespoon olive oil and in batches add the butternut squash, You want to brown them on all side so add them to the pot and leave them for 5-6 minutes. then turn them over and leave them again for 5-6 minutes. The goal is to make them as brown as you can; this is what will give you a deep carmelized flavor. Remove the pieces of browed squash to a bowl. Depending on how browned your pan got, you can add a little of the broth and scrape up any bits; add this to the bowl. Continue with the rest of the squash. Once all pieces are browned, you can leave the last batch in the pot.
finely chop 4 of the sage leaves and add them to the pot. Add the diced onion and garlic and cook, scraping up any bits from the bottom of the pan. continue cooking until the onion is translucent and just starting to get lightly browned around 9-10 minutes. Add the set aside squash back into the pot. add the broth and bring to a boil. Reduce the heat to low and simmer until the squash is tender and starting to fall apart. about 20 minutes.
While the soup is simmering. in a small saute pan add some olive oil, enough to cover the bottom. bring the oil over medum heat to shimmering hot temperature. In batches your going to fry the sage leaves just till crisp; only like 10-15 seconds. Drain on a papertowel.
Either use an immersion blender or a blender and blend until smooth. I don't mind leaving some chunks but you do you. Return the soup to the pot if you used a blender. Add the cream and simmer for about 5 minutes till it is warmed through.
Place some proscuitto pieces into the bottom of your bowl, add the soup and top with a little heavy cream, another piece of proscuitto and a fried sage leaf.