Pat the shrimp dry. Moisture is the enemy of a good sear. Use paper towels to blot the shrimp until dry.
Mix the Cajun seasoning. In a small bowl, combine salt, black pepper, smoked paprika, cayenne, oregano, thyme, onion powder, and garlic powder. Stir well.
Season the shrimp. Toss the shrimp with the oil, then sprinkle the spice mix evenly.
Coat thoroughly so every piece gets flavor.
Heat your pan. Place a large skillet over medium-high heat. Add butter or ghee. When it’s hot and foamy, you’re ready.
Cook in batches. Add shrimp in a single layer.
Cook 1.5 to 2 minutes per side until the shrimp turn opaque and lightly browned. Avoid crowding the pan so they sear, not steam.
Add garlic and lemon. During the last 30 seconds of the final batch, add minced garlic. Stir just until fragrant.
Turn off heat, then add lemon zest and a good squeeze of lemon juice.
Taste and adjust. Add a pinch more salt, a touch of cayenne, or another squeeze of lemon as needed. Garnish with parsley.
Serve immediately. Pair with cauliflower rice, zucchini noodles, or a crisp salad. Spoon any pan juices over the top.