In a large pot of boiling water, cook spinach just until wilted, about 30 seconds. Drain and rinse with cold water to stop the cooking process. Squeeze out as much water as you can.

Mix with remaining ingredients, then set aside.

Preheat oven to 450 degrees Fahrenheit. Line a baking sheet with Gefen Parchment Paper and brush a bit of olive oil on the parchment.

Cut a slit on one side of each fillet, in the thickest part of the fish, forming a pocket in the salmon. Dividing the spinach mixture evenly between the fillets, generously stuff the pocket. (If you are preparing this dish in advance, refrigerate or freeze at this point and bake just before serving.)

Place fillets, skin-side down on the pan. Brush with additional olive oil. Bake for 15 to 17 minutes. Serve hot.