Gather all ingredients.

Melt butter in a large pot over medium heat. Add onion and garlic; cook and stir until softened and browned, 7 to 10 minutes.

Stir in broth, butternut squash, curry powder, salt, cumin, and cayenne pepper; bring to a boil. Reduce the heat to low and simmer until squash is tender, about 15 minutes. Remove from the heat.

Stir in half-and-half and honey. Puree soup with an immersion blender until smooth.

Ladle soup into serving bowls and top with a sour cream dollop.