Trim escarole and place in bowl of cold water to rinse well. Strain and chop in large pieces. Set aside.
Wash, peel, and and quarter potatoes. Then cut into ¼” thick slices. Set aside.
Remove outer leaves of leeks and discard. Trim off dark green leaves and freeze in plastic bag to save for future stock. Slice down the length of leeks and rinse well, opening each layer to reveal the inner parts. Slice thinly. Set aside.
Remove outer skins of shallots. Slice thinly. Set aside.
Peel garlic and mince. Set aside.
If using rind, wash and scrape a thin layer from the outside. Set aside.
Heat olive oil in large soup pot. Add shallots and saute a few minutes. Add leeks and stir for a few minutes. Add garlic and stir. Do not brown garlic. (Add hot pepper flakes if using.) Add potatoes.
Add enough water to completely submerge the vegetables by about 5cm. Bring to a boil and then reduce heat to simmer. Add rind, if using. Season lightly with salt and pepper Set lid to cover partially. Simmer for about 30 minutes, or until potatoes are tender.
Then, rinse rice and add to soup. Add chopped parsley and chopped escarole. Sir and simmer for about another 20 minutes or until rice is tender, stirring occasionally. Add more water if needed.
Taste for seasonings. (Remove rind, if using. Can be finely chopped and added to soup.) Stir and serve immediately. Add freshly grated Parmigiano Reggiano and a drizzle of extra virgin olive oil.