If possible, season the pork shoulder the night before with the fennel anise salt (note: I didn’t do this and it was still delicious).
Preheat the oven to 325.
Toast the fennel seeds in a small pan for about 1 minute until they are fragrant. Wrap them in cheese cloth with the bay leaves and tie together with kitchen string to make a sachet.
Heat a dutch oven over medium-high heat. Add olive oil and heat until just smoking. Sear the pork in batches until golden brown all over. Remove the pork to a plate. Decrease the heat to medium and add the leeks and fennel and cook until soft and translucent, about 8 minutes. Add the garlic and cook for 2 more minutes. Add the white wine and reduce until the pan is almost dry. Add the chicken stock and the sachet and return the pork to the pan. Bring to a boil then lower to a simmer, cover, and place in the oven for about 2 hours. The pork should be fork tender when you are finished. Discard the sachet.