Heat a non-stick pan and add the oil. Pan-sear your salmon about 3-4 minutes per side. Transfer to a plate and set it aside.
Add the butter into the pan. Then add the minced garlic and onions. and cook for about 1-2 minutes. Pour the cream, and let it simmer. Add the cheese, lemon zest and juice, and then the spinach.
Add the cooked salmon back into the pan. Turn off the heat and let it sit there for another 5 minutes for the salmon to soak in the creamy sauce. You can spoon some sauce over the salmon as well. Enjoy with some salad or brown rice.