Preheat the oven to 425°F. Spread the cubed butternut squash in a single layer on a foil-lined baking sheet. Drizzle with 2 tablespoons of the canola oil and sprinkle with the ½ teaspoon kosher salt; toss to coat. Roast for 15 minutes, until the squash is caramelized but not browned. Remove from the oven and set aside.
Heat a dutch oven or heavy-bottomed pot over medium. Add the butter and the remaining 1 tablespoon canola oil and melt. Add the diced onion, diced carrot, and pressed garlic and cook, stirring frequently, until the onion is softened, about 5 minutes.
Add the roasted squash to the pot, then pour in the chicken stock (4 cups). Add the bouquet garni (sage, thyme sprigs, rosemary, parsley). Bring to a boil, reduce to a simmer, and cook until the carrots are tender and the flavors have melded, about 15 minutes. Stir in the honey.
Remove and discard the bouquet garni. Let the pot cool slightly (a few minutes) so it is safe to blend. Working in batches if needed, transfer the vegetables and broth to a blender. Leave the blender lid vented (remove the center plug) and cover the lid opening with a clean dish towel to allow steam to escape while preventing splatter. Blend each batch until completely smooth.
Return the blended soup to the pot. Stir in the cream or whole milk (1 cup). Warm the soup over medium heat for about 5 minutes, stirring occasionally, until heated through. Taste and adjust seasoning as needed.
To serve, thin the sour cream (amount as listed in the ingredients) with 1–2 teaspoons of water or milk, whisk until smooth, and drizzle over each bowl of soup.