In a large Dutch oven or heavy-bottomed pot, melt unsalted butter over medium heat. Add finely chopped onions, garlic, and ginger, seasoning lightly with kosher salt and freshly ground black pepper. Cover and cook, stirring occasionally, until the vegetables are tender, about 5–6 minutes.

Introduce peeled and cubed butternut squash to the pot. Cover and cook, stirring intermittently, until the squash is just tender when pierced with a fork, approximately 4–5 minutes. Stir in tomato paste and smoked paprika, allowing the mixture to cook for an additional 1–2 minutes until the tomato paste darkens slightly.

Add pumpkin puree and 6 cups of vegetable broth to the pot. Partially cover and bring to a boil over high heat. Once boiling, reduce the heat to medium-low and simmer, stirring occasionally, until the squash is thoroughly tender, roughly 15 minutes.

Remove the pot from heat. Using an immersion blender, puree the soup until completely smooth. Alternatively, allow the soup to cool slightly and blend in batches in a standard blender. If the soup is too thick, gradually add additional broth, 1/4 cup at a time, until the desired consistency is achieved. Taste and adjust seasoning with salt and pepper as needed.

Serve the soup in bowls, finishing with a swirl of cream or a dollop of sour cream. Garnish with roasted pumpkin seeds if desired for added texture and visual appeal.