Rinse the deveined shrimp and pat dry with paper towels.
Add shrimp blackening spices to a small bowl and stir to combine; set aside.
Place a clean, dry frying pan or cast iron skillet over high heat until it starts to smoke. Keep kitchen area well ventilated.
Toss the shrimp in melted butter and then dredge both sides in blackening spices. Press spices to adhere if necessary.
Immediately sear shrimp in preheated pan over high heat for 30-60 seconds on each side. Don't overcook, as they will dry out. Serve immediately with slices of lemon. Or, use them as part of another recipe, like shrimp and grits.
If you have never cleaned shrimp, don't worry; it's very easy to do. There are instructions on how to peel and devein shrimp in my Cajun Shrimp and Rice recipe post.