Start by patting the fish fillets dry and rubbing them with olive oil. Season both sides with the blackened seasoning and a pinch of salt and pepper. Do the same with the shrimp in a separate bowl, adding a splash of lemon juice to brighten the flavor.
Heat a nonstick skillet or cast iron pan over medium-high heat. Add a little oil and sear the fish for about 3 to 4 minutes per side, depending on thickness, until the exterior is blackened and the inside is flaky. Remove and keep warm.
In the same pan, add the shrimp and cook for 1 to 2 minutes per side until they turn pink and are lightly charred. Remove and set aside with the fish.
Reduce the heat to medium-low and melt the butter in the pan. Add the minced garlic and cook for 30 seconds until fragrant. Pour in the heavy cream and whisk in the Dijon mustard and Parmesan cheese. Let the sauce simmer gently for about 3 minutes until slightly thickened. Taste and adjust seasoning with salt and pepper.
Return the fish and shrimp to the pan and spoon the sauce over them. Let everything heat together for about a minute.
Serve hot over rice with sautéed vegetables on the side. Spoon extra sauce on top for the perfect finish.
This dish packs flavor with every bite, balancing the smoky blackened seasoning with a silky, garlicky cream sauce that ties it all together.