In a large skillet over medium heat,add butter and oil. Once butter is melted add onion and garlic. Saute until vegetables are softened.
Add baby spinach to onion mixture,sook until spinach is wilted and glossy.
In a large mixing bowl,mix your salt pepper,sour cream,mayo,mustard,1/4 cup parmesan cheese.Set aside 1/2 cup of the sour cream mixture.
Mix in rice,and spinach mixture,add your egg beaters,and mix well.
Grease a large baking dish with cooking spray,or olive oil. Spoon in all of your rice mixture. Place salmon on top ,and cover with 1/2 cup of the sour cream mixture.Sprinkle the remaining cheese over sour cream mixture.
Bake at 350 for 25-30 minutes,or until fish flakes apart.