Heat olive oil in a heavy pot over medium. Add onion and cook for 6 to 8 minutes until soft and lightly golden.
Add garlic, ginger, sage and nutmeg; stir for 45 seconds until fragrant without browning the garlic.
Stir in pumpkin until it coats the aromatics, then gradually whisk in broth, salt and pepper until smooth.
Bring to a gentle simmer and cook partially covered for 15 minutes, stirring the bottom occasionally.
Blend until completely smooth, then stir in coconut milk over low heat. Do not boil hard after adding it.
Add lemon juice, taste for salt, and thin with broth if needed. Serve with pumpkin seeds after a 5-minute cooling rest.