In a large pot, melt 1 Tbsp butter. Add onion and garlic, sauté until soft and fragrant.
Stir in cubed butternut squash. Cook for 3–4 minutes.
Pour in vegetable broth. Bring to a boil, then reduce to simmer. 4. Cover and cook 20–25 minutes, until squash is tender.
Use an immersion blender (or transfer in batches to a blender) to puree until smooth. 6. Stir in milk or cream. Adjust seasoning with salt and pepper.
In a small skillet, melt remaining 2 Tbsp butter over medium heat until golden and nutty. 8. Add sage leaves and fry until crisp. Remove and drain on paper towel.
Ladle soup into bowls. Drizzle with brown butter, top with sage leaves, and enjoy.