Pat the shrimp very dry. Toss with avocado oil, Cajun seasoning, paprika, sea salt, and cayenne. Let it rest while the pan heats.
Heat a large skillet (preferably cast iron) over medium-high heat, then add butter and let it foam.
Cook shrimp in a single layer for 90 seconds without stirring, then flip and cook for 60–75 seconds until opaque. Remove if done early.
Lower the heat to medium-low. Push shrimp to the sides of the pan.
Add the remaining butter and garlic to the center. Cook 45–60 seconds, stirring until fragrant but not browned.
Add hot sauce and lemon juice. Toss shrimp over low heat for 30–45 seconds until glossy.
Turn off the heat, garnish with parsley, and serve immediately.
Notes
You can substitute large shrimp with jumbo (add extra cook time), avocado oil with grapeseed or canola oil, and Cajun seasoning with Creole or blackened seasoning if needed; dried parsley can be swapped for fresh parsley or cilantro
Adjust heat to taste: omit cayenne for mild, prepare as written for medium, or add extra cayenne and a few more dashes of hot sauce for hot
Don't crowd the skillet; shrimp release moisture and will steam instead of sear if overcrowded. Cook in batches if needed
Store leftovers in an airtight container in the fridge for up to 3 days or freezer for up to 2 months
Reheat gently in a skillet over low heat, adding a splash of water if needed to loosen the glaze