Start by sprinkling ¼ teaspoon of salt over the shrimp in a colander and let them rest for 1 minute. Then rinse off the salt and thoroughly pat the shrimp dry with paper towels.
Next, mix together the butter, garlic, chopped cilantro or parsley, and the cajun seasoning until fully combined. Keep this flavorful butter ready for cooking.
Warm the olive oil in a large skillet over medium heat, then add the shrimp in a single layer—even if some overlap slightly. Cook them for about 1 minute until they just start to turn pink.
Lower the heat to medium-low and add the spiced butter mixture to the pan. Stir the shrimp gently but continuously, coating them well with the seasoned butter. Keep cooking for another 1 to 2 minutes until the shrimp are fully cooked, firm, and opaque throughout.