In a large roasting pan, mix the butternut squash and the onion, drizzle with olive oil and sea salt.
Take about 12 inches of parchment paper and place garlic in centre. Drizzle with olive oil and sea salt. Wrap tightly, and then wrap parchment in foil (I don’t like putting foil directly on food, but it’s up to you!). Place this package beside the roasting pan in the oven.
Bake for about 45 minutes or until squash is tender and garlic is mushy.
Add the squash and onion (and all the pan juices) to a glass blender and blend adding stock to desired consistency. Squeeze out garlic and add (with all the olive oil from the little package) into the squash purée and continue to blend until smooth.
Add to a large sauce pan and mix in milk and Parmesan. Bring to a simmer.
Simmer for 10 minutes and serve with a drizzle of Olive oil and additional Parmesan.