In a large bowl whisk together the melted butter with the salt, cayenne powder, cajun seasoning, sweet paprika, and minced garlic.
Add the shrimp to the butter mixture and mix well to combine. Set aside.
Cut eight large pieces of heavy-duty foil, stacking one on top of the other. Place one-fourth of the cajun seasoned shrimp directly in the center of the foil sheet. Place asparagus to one side of the shrimp going the long direction of the foil. Place one tablespoon butter on top of asparagus and sprinkle with salt and pepper.
To close the packet- use two pieces of foil per packet -fold the edges of foil up and around the shrimp and asparagus to create a closed packet. Avoid wrapping too tight as air circulation within the foil pack is good.
For the grill: Set grill to medium-high heat. Transfer foil packs to the grill, seam-side-up. Cook for approximately 8 minutes, or until shrimp are bright pink.
For the oven: Preheat oven to 400 degrees F. and place foil packets on top of a baking sheet. Bake for approximately 10-15 minutes, or until shrimp is cooked through and bright pink.
Garnish shrimp and asparagus with fresh chopped parsley and lemon wedges, if desired. Enjoy!