Combine all spice ingredients in a small bowl. Stir well to combine.
Pat salmon filets dry and brush flesh side with melted butter. Reserve any excess butter for later.
Spoon spices on top of butter-coated salmon. Gently pat down to create a nice crust.
Heat large heavy bottom pan or cast iron skillet over medium-high heat (my induction burner was set to 8 out of 10). When the pan is hot, add the olive oil and any remaining butter.
Place the salmon filets, seasoning side down and skin side up, onto the oil-coated hot pan. Cook until a golden to dark brown crust forms on the bottom. Try not to move them around much but you can gently peek underneath to see when they are done.
When the filets are ready to flip, transfer them to a plate, skin side down. Then, use a rubber spatula to scrape as much of the seasoned butter to a small dish. This will be used to spoon over the salmon when it's served. Return the skillet to the heat.
Place the filets back in the hot pan, skin side down, and continue cooking until the internal temperature of each filet reaches 125°F.
The skin should stick to the pan and you can use a spatula to lift the filet off to serve. Spoon on additional melted butter from the pan, if desired, and a generous squeeze from a lemon.