Ingredients:

4 slices white sandwich bread , torn into pieces
1/2 cup mayonnaise
1/4 cup bottled clam juice (No clam juice? Substitute chicken stock)
1/4 cup finely chopped fresh parsley
4 scallions , chopped fine
2 garlic cloves minced
2 teaspoons grated zest and 1 tablespoon juice from 1 lemon
1 tablespoon Dijon mustard
1/8 teaspoon cayenne pepper
Salt
1 1/4 pounds colossal shrimp, peeled and deveined

Instructions:

Adjust oven rack to upper-middle position and heat oven to 375 degrees. Pulse bread in food processor to coarse crumbs. Transfer crumbs to broiler pan bottom and bake until golden and dry, 8 to 10 minutes, stirring halfway through cooking time. Remove crumbs from oven and reduce temperature to 275 degrees.
Combine toasted bread crumbs, mayonnaise, clam juice, parsley, scallions, garlic, lemon zest and juice, mustard, cayenne, and ¼teaspoon salt in large bowl.
Pat shrimp dry with paper towels and season with salt. Grease empty broiler pan bottom. Following steps 1 to 4 at left, butterfly and cut hole through center of each shrimp and arrange cut-side down on prepared pan. Divide bread crumb mixture among shrimp, pressing to adhere. Bake until shrimp are opaque, 20 to 25 minutes.
Remove shrimp from oven and heat broiler. Broil shrimp until crumbs are deep golden brown and crispy, 1 to 3 minutes. Serve.