01 - Bring a large pot of salted water to a rolling boil. Add the trimmed and halved Brussels sprouts, cooking for 4–5 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 softened and fragrant.
03 - Add the blanched Brussels sprouts to the skillet and sauté for 3–4 minutes, tossing occasionally, allowing them to develop a light golden-brown color on the edges.
04 - Pour in the broth and let it simmer for 1 minute to reduce slightly. Reduce the heat to low, then add the Boursin cheese. Stir continuously until the cheese is completely melted and forms a smooth, creamy sauce coating the sprouts evenly.
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.