Heat a large pot over medium-low heat. Remove the outer layer from the onion and slice the entire thing into rings. Heat 1 tbsp of oil in the pot and add the onion.
Caramelize the onions by allowing them to cook on medium-low heat for about 40 minutes, stirring every 5-10 minutes.
While onions are caramelized, peel and roughly chop the butternut squash, removing the inside seeds.
Roughly chop the carrots and granny smith, and mince the garlic.
Once the onions have caramelized for 40 minutes, add the 1/4 cup balsamic vinegar and deglaze the pan, getting all of the bits from the bottom.
Add the minced garlic, butternut squash, carrots and apple to the pot. Cook for about 10 minutes, stirring every few until veggies are slightly softened.
Season with the 2 tsp salt and 1 tbsp Italian seasoning and add the 4 cups vegetable broth. Bring to a simmer and cook until the vegetables are fork tender, about 30 minutes.
Using an immersion blender, blend the soup until it is about halfway blended and more liquid is needed.
Add the can of coconut milk and continue to blend until the soup is silky smooth!