In a medium pan, turn the heat to medium add olive oil and salmon. Cook the salmon until both sides are no longer pink and appear cooked.
Move the salmon to a plate once.
Turn the heat off and add all-purpose-flour, whole milk, bouillon, and butter to the pan. After mix everything, turn the heat to low, then stir until the it gets little thicker.
Then add the salmon, cut spinach and mushrooms. Cover with a lid and simmer for 8 minutes with low heat.
Add black pepper to finish.