In a large saucepan over medium heat, melt the butter.
Sauté the onion until slightly translucent, about 5 minutes.
Add the garlic, and stir, cooking for an additional 2 to 3 minutes.
Pour the chicken broth into the pan, and bring to a boil.
Add the broccoli, and stir.
Reduce the heat to a simmer, and cook for 10 to 15 minutes, or until the broccoli has softened.
Add the coconut milk, season with salt and pepper, and either transfer to a blender or use an immersion blender to blend the soup until it is smooth.
Serve hot.