Heat a large Dutch oven over medium-high heat with extra-virgin olive oil a couple of turns of the pan. Add the pancetta, if using, the onions and the garlic. Stir occasionally for 3 to 4 minutes, then add the potatoes and season with salt and pepper, to taste. Cover the pan and cook for 5 minutes more, stirring occasionally. Add the escarole and season with nutmeg, cover the pan and let wilt for 2 minutes. Stir in the stock and water and bring the soup to a boil. Reduce the heat and simmer 15 minutes for flavors to combine, adjust salt and pepper, to taste, and let cool. Store for a make-ahead meal. Bring the soup, covered, to a boil over medium-high heat. Add the peas and ditalini and cook to al dente, about 7 to 8 minutes. Turn off the heat and serve in shallow bowls garnished with pesto.

Pesto:

Put the herbs into food processor along with the nuts and grated garlic. Season with salt and pepper, to taste, then add the lemon zest, extra-virgin olive oil and the cheese. Pulse into a coarse paste, then transfer the pesto to storage container and drizzle the top with a thin layer of extra-virgin olive oil to retard browning. Cover and store in the refrigerator. Bring to room temp when ready to use.