Season the salmon liberally with all of the spices (only season meat side, not skin side). Add olive oil to a cast iron skillet and heat over medium high.
Once the olive oil is heated, add the salmon skin side down. Sear for 5 minutes, then flip it over. Sear for an additional 5 minutes. Remove salmon and set aside. Salmon should have a nice brown crust, but may not be cooked all the way through.
Add butter to the pan. Next add the sliced mushrooms. Sauté for 5 minutes, or until mushrooms start to get soft.
Pour red wine into the pan and stir to get up all of the brown bits. Add the heavy cream and chicken stock.
Remove thyme "leaves" from the sprigs of thyme and stir them into the sauce until combined.
Stir the spinach into the sauce. Nestle the salmon back into the cream sauce and continue to simmer for 7-10 minutes.
Notes
Regular non-stick skillet can be used, but cast iron skillet is ideal to achieve the perfect blackening for the salmon.