Preheat the oven to 400 degrees. Line a large baking sheet with parchment paper or foil.

Peel, seed, and cut the butternut squash into 1 1/2-inch chunks. Transfer the squash to a large bowl, add the olive oil, 1/2 teaspoon salt, and 1/4 teaspoon black pepper and toss to coat. Transfer the squash to the prepared pan and spread out in an even layer.

Roast for 15 minutes. Flip and roast for 15 to 20 more minutes, until the squash pieces are fork-tender and slightly caramelized (not charred). Set aside.

Melt the butter a large saucepan or stock pot over medium heat. Add the onion and cook until soft and lightly caramelized (we’re not looking for lots of caramel color here), about 8 to 10 minutes. Add the garlic, ginger, thyme, sage, 1/2 teaspoon salt, and 1/4 teaspoon black pepper and stir to coat. Cook for 30 seconds to 1 minute, until the herbs are fragrant.

Add the roasted butternut squash and stir to combine.

Add 4 cups of the broth and bring to a simmer. Simmer for 5 minutes.

Puree the soup with an immersion blender, or cool the soup slightly and, working in batches, puree in a blender until smooth. If you prefer a thinner soup, add more broth. Season to taste with salt and black pepper.

Ladle the soup into bowls and top with pumpkin seeds, croutons, and parsley if desired.