In a large saucepan, melt the butter over medium heat. Add the onions and cook, stirring occasionally, until softened and lightly golden, about 8 minutes. Add the potatoes and zucchini and season with salt. Pour in the chicken broth and bring to a boil; cover, lower the heat and simmer until the vegetables are tender, about 20 minutes.
Using a blender, partially puree the soup, leaving some chunks. Stir in the ham, dill and nutmeg and serve with the bread.
