In a medium stock pot over medium heat, add butter and olive oil. When the butter melts, add the onions, celery and carrots and cook until browned, about 10 minutes. Add the zucchini, pear and sage. Cook another 10 minutes, stirring occasionally. Add the water, potatoes, and 1 teaspoon salt.

Place a lid on the pot and reduce heat to low. Simmer until the vegetables are fork-tender, about 30 minutes.

Remove the soup from the heat. With an immersion blender, puree the soup until smooth. Stir in the heavy cream. More water can be added as desired if the soup is too thick. Bring to a simmer and season with salt and pepper. Serve with bread or croutons.