Preheat the oven to 425 F | 220 C. In a skillet over high heat, melt the butter. Saute the onions and celery for 2-3 minutes, until softened. Then add the red pepper and jalapeno. Cook for another 2-3 minutes, until tender, then add the garlic. Stir until the garlic is fragrant.
Add the crayfish to the skillet and cook for 3-4 minutes, until the crayfish are cooked through. Reduce the heat to medium. Add the juice of half of a lemon and season with the cajun spice blend, Louisianna Hot Sauce and white pepper. Stir to cover the crayfish in spices.
Stir the panko into the skillet. Cook for a few minutes until the panko has adhered to the crayfish and absorbed any excess moisture. Remove from the heat. Cool for about 15 minutes. Add the cream cheese and egg yolk and stir well to combine everything together. Chill until ready to stuff the filets.
Make cut lengthwise down the center of the catfish filet, but do not cut all the way through. You may need to run the knife down the center a couple times to achieve a smooth cut. Place the knife flat on the filet and make a slice along the inside of the center cutter - again not cutting all the way to the edge of the fish - effectively creating a pocket on the inside of each side of the filet.
Gently open the filet and stuff generously with the crayfish filling. Pile the excess filling on the top of the filet. Place the filets in a baking sheet lined with the cut lemon slices and a sprig or two of thyme. Drizzle with olive oil and season with salt and pepper, to taste. Bake for 20 minutes, until the fish is cooked through and flakes easily. Broil for an additional 5-10 minutes, until the top is crispy and golden brown.
While the fish cooks, mix together the remoulade ingredients. Chill until ready to serve.
When the fish is done cooking, carefully remove it from the pan. Discard the lemon and thyme sprigs. Serve the stuffed catfish on a bed of jambalaya rice and with a hearty dollop of remoulade. Enjoy!