Heat the broiler on high and set an oven rack directly below the heating element (4 inches below). Line a large, rimmed, broiler-safe baking sheet with foil (for easy cleanup).
Generously spray both sides of the salmon fillets with olive oil.
Place the fillets in the pan, skin side down. Sprinkle their tops with kosher salt, black pepper, garlic powder, and dried thyme.
Lightly spray the tops again with oil to help keep the spices (especially the thyme) moist and prevent them from burning under the broiler.
Broil the salmon until opaque and cooked through, for about 4 minutes. Serve immediately.
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Notes
There's no need to remove the skin.
There's no need to flip the fish midway through cooking.
To ensure the salmon is ready, gently flake its top with a fork. When fully cooked, the flesh will separate easily. If undercooked, the flesh will resist flaking.
When broiling, pay close attention to the food and make sure it doesn't burn. Sometimes it helps to keep the oven door slightly ajar.
This recipe works with ½-inch thick salmon fillets. If your salmon fillets are thicker, broil them 6 inches below the heating element for 5-6 minutes.
You can keep the leftovers in the fridge, in an airtight container, for up to 3 days. They dry out when reheated, so I like to flake them cold and mix them into a salad the next day for lunch. If you decide to reheat the leftovers, do so in the microwave, covered, at 50% power.