Preheat the oven to 375°F.
Scrub or peel the carrots, then cut them into small 2-inch pieces and halve each piece.
Chop the onion into large chunks.
Peel all the garlic cloves.
Place the vegetables, thyme, and sage on a baking sheet lined with parchment paper. Drizzle with oil and sprinkle with salt. Roast for 35 to 40 minutes or until the carrots are fork-tender.
If using small pumpkins as serving bowls, slice off the tops and scrape out the seeds. Place the pumpkins upside down on a baking sheet lined with parchment paper. Drizzle with oil and bake for 35 minutes.
In a large pot, combine all the roasted vegetables, pumpkin puree, and vegetable broth.
Using an immersion blender, blend all the ingredients until smooth. If the soup is too thick, add more vegetable broth to reach your desired consistency.
Ladle the soup into bowls or the roasted small pumpkins (if using).
Top with pesto and pumpkin seeds for added flavor and texture.
Serve hot and enjoy!