Preheat oven to 180°C. Combine lemon juice and olive oil in a small bowl.
Mix shallots and olives together in a small bowl. Combine with the Boursin cheese.
Fold 1 (8"by 8") piece of nonstick baking paper, or tin foil in half to form a loose parcel.
Place the cod fillet into the parcel and add the lemon and olive oil followed by the shallot and olives and Boursin cheese. Place nonstick baking paper parcel on a baking sheet and bake 15 minutes, until the paper has puffed up.
The cod should be opaque and flake easily in the center. If it is not fully cooked, bake an additional 3-5 minutes. Serve immediately.