Pre-heat oven to 425°F.
Place the squash and onion on two baking sheets. Toss with the olive oil and then sprinkle with salt and pepper.
Bake for 45 minutes, tossing occasionally, until tender.
Once the squash and onion are out of the oven, heat butter over medium heat in a large skillet.
Add the garlic and ginger and saute until fragrant, about 3 minutes.
Stir in the roasted squash and onions.
Add in 4 cups of the stock and simmer for 20 minutes.
Puree mixture in blender, or food processor, until smooth (be careful, liquid is hot!).
Clean out skillet and then pour pureed mixture into it over medium heat. Stir in the remaining 2 cups of stock.
Add 1 ½ teaspoons of Kosher salt and 1 tsp pepper.
Add curry and mix. Cook until heated through, about 5 minutes.
Garnish with homemade croutons.