Place the salmon fillets on a baking sheet lined with parchment paper. Rub with 1/4 of the olive oil and season with salt.
Wrap the parchment around the salmon, folding the seams and tucking them so that steam doesn’t escape. Bake until medium-rare, about 18 minutes.
Meanwhile, place spinach in a steamer over boiling water for about 3 minutes or until wilted. Drain any excess water. Coat spinach with remaining oil and season with salt to taste. Divide onto plates and top with the salmon. Enjoy!