Preheat oven to 350 degrees. Coat 1.5 quart baking dish with cooking spray (I use a 9 inch pie plate).
Place spinach in microwavable dish with 3 Tbs. of water. Cover and microwave on high for 3 minutes. Drain well.
In a large bowl, stir together spinach, rice and 1/4 tsp. salt. Make sure spinach is evenly distributed throughout rice.
In a small bowl whisk together sour cream, egg, 2 Tbs. of the parmesan cheese, mustard, pepper and remaining salt. Set aside 2 Tbs. of sauce. Combine remaining sauce with rice-spinach mixture. Stir until well coated. Spread in baking dish, leveling smooth.
Slice salmon, crosswise at an angle, into 1/2 inch thick slices. Fan slices over rice mixture in whatever way pleases your eye.
Thin reserved sauce with 1/2 tsp. water and drizzle over salmon. Sprinkle remaining parmesan cheese over all.
Bake, uncovered, for 30 minutes. Let stand 5 minutes at room temperature before serving. Enjoy.