Preheat your oven to 425°F and line a baking sheet with parchment paper. Cut the butternut squash in half, scoop out seeds, brush cut sides with 1.5 tbsp olive oil, and season generously with salt and pepper. Roast cut-side down for 25-28 minutes until the flesh is fork-tender and deeply caramelized.

While the squash roasts, heat remaining olive oil in a large pot over medium heat. Add diced onion and cook for 5 minutes until softened and translucent, then add minced garlic and cook for 1 minute until fragrant—this builds the aromatic foundation for your soup.

Once the roasted butternut emerges from the oven, let it cool for 3 minutes, then scoop the caramelized flesh into your pot with the onion mixture. The creamy roasted butternut soup elegant depth begins forming as these components combine.

Pour in vegetable broth and bring the mixture to a simmer, cooking for 8 minutes to meld flavors. Using an immersion blender, puree the soup until completely smooth—this step requires patience for optimal creaminess.

Reduce heat to low and stir in heavy cream, fresh thyme, nutmeg, cayenne pepper, and season with salt and pepper to taste. Simmer for 3 minutes without boiling, as high heat can break the cream.

While the soup finishes, melt butter in a small skillet over medium-low heat with sage leaves. Cook for 4-5 minutes until the butter turns golden brown and fragrant, watching carefully to prevent burning.