Mix the 2 tbsp brown sugar, 1 tsp smoked paprika, 1 tsp garlic powder, 1/2 tsp onion powder, 1/2 tsp kosher salt, 1/4 tsp black pepper, and 1/4 tsp cayenne in a small bowl. Pat all 4 fillets dry with paper towels and press the rub firmly onto the flesh side of each.

Heat the 2 tbsp olive oil in a large skillet over medium-high heat until shimmering, about 2 minutes. Sear the fillets rub-side down for 3 to 4 minutes, then flip and sear the skin side for 2 to 3 minutes until the internal temperature reads 125°F to 145°F (52°C to 63°C).

Reduce heat to medium-low. Push fillets to one side and add the 3 tbsp unsalted butter. Once melted, add the 3 cloves minced garlic and cook for 30 seconds, then baste the fillets with the butter 3 or 4 times.

Add the 1 tbsp lemon juice to the pan and stir. Plate the fillets, spoon the garlic butter over the top, scatter the 1 tbsp chopped parsley over each, and serve with lemon wedges alongside.