01 - Bring a large pot of salted water to a rolling boil. Add the trimmed and halved Brussels sprouts, cooking for 4 to 5 minutes until just tender. Drain thoroughly and set aside.
02 - In a large skillet over medium heat, melt the unsalted butter. Add the finely chopped shallot and sauté for 2 minutes until fragrant and softened.
03 - Add the blanched Brussels sprouts to the skillet and sauté for 3 to 4 minutes, allowing them to lightly brown and develop a golden crust.
04 - Pour in the broth and let it simmer for 1 minute. Reduce the heat to low, add the Boursin cheese, and stir continuously until the cheese melts into a smooth, creamy sauce that evenly coats the sprouts.
05 - Season with salt and freshly ground black pepper to taste. Remove the skillet from heat.
06 - Transfer to a warm serving dish. Garnish with chopped fresh parsley and lemon zest if desired. Serve immediately while hot.