Preheat your oven to 400°F and line a baking sheet with parchment paper. Toss pumpkin cubes with 2 tbsp olive oil, salt, and pepper until fully coated. Roast for 20-25 minutes until the edges are deeply caramelized and flesh is fork-tender.

While pumpkin roasts, warm the remaining 1 tbsp olive oil and butter in a large pot over medium heat. Sauté diced onion for 5 minutes until softened and fragrant, stirring occasionally.

Add minced garlic to the pot and cook for 1 minute until the aroma blooms throughout your kitchen. Pour in vegetable broth and bring the mixture to a gentle simmer.

When creamy hearty roasted pumpkin soup reaches simmering point, add the roasted pumpkin cubes to the broth. Stir in nutmeg, cayenne pepper, and fresh sage, then simmer for 5 minutes to allow flavors to meld together beautifully.

Remove the pot from heat and let it cool slightly, about 2 minutes. Working in batches, carefully transfer the mixture to a blender and puree until completely smooth and silky.

Return the pureed soup to the pot over low heat and stir in heavy cream, coconut milk, and maple syrup. Heat through for 3-5 minutes without boiling, stirring frequently to incorporate all ingredients evenly.

Taste and adjust seasonings as needed, adding more salt or nutmeg according to preference. Toast pumpkin seeds in a dry skillet for garnish before serving immediately.