01 - Preheat the oven to 400°F. Line a baking sheet with parchment paper or lightly grease a baking dish.
02 - Pat the salmon fillets dry with paper towels. Arrange them on the prepared baking sheet, skin side down.
03 - In a small bowl, mix Boursin cheese, chopped shallot, and Dijon mustard until creamy.
04 - Season the salmon with salt and pepper, then spread the Boursin mixture evenly on top of each fillet.
05 - Scatter chopped spinach around the salmon on the baking sheet. Drizzle olive oil over the spinach and salmon.
06 - Top each fillet with a couple of lemon slices.
07 - Bake for 15-20 minutes, or until the salmon flakes easily with a fork and the cheese topping is lightly golden.
08 - Garnish with fresh dill or parsley before serving.