I start with the potatoes since they take the longest. I add the cubed russet potatoes to a large pot of salted water and boil them for about 15-20 minutes, until a fork slides in easily. Once drained, I mash them with butter, warm milk, salt, and pepper until they're smooth and creamy.

While the potatoes boil, I pat the salmon fillets and shrimp completely dry with paper towels. This step matters more than people think, since a dry surface helps everything sear instead of steam. I coat both generously with Cajun seasoning, salt, and a little pepper.

I heat olive oil and a tablespoon of butter in a large skillet over medium-high heat. Once it's shimmering, I lay the salmon in skin-side down and let it cook undisturbed for 4-5 minutes. I flip it carefully and cook another 3-4 minutes until it flakes easily.

Using the same skillet, I add the shrimp in a single layer so they cook evenly. It only takes 2-3 minutes per side until they turn pink and opaque. I pull them out right away, since overcooked shrimp turn rubbery fast.

In that same flavorful skillet, I melt the remaining butter and toss in the minced garlic, letting it sizzle for about 30 seconds until fragrant. I pour in the heavy cream and chicken broth, whisking constantly to lift up all those browned bits stuck to the pan.

Once the cream mixture starts to bubble gently, I stir in the Parmesan cheese and lemon juice, letting it simmer for 2-3 minutes until it thickens enough to coat the back of a spoon. I taste and adjust the salt and pepper here.

I return the salmon and shrimp to the skillet, spooning the warm garlic cream sauce generously over the top so everything reheats gently. I let it sit for a minute so the seafood soaks up the sauce before plating.

Finally, I spoon a generous scoop of the mashed potatoes onto each plate, top it with the salmon and shrimp, and drizzle extra sauce over everything. A sprinkle of fresh parsley on top makes it look like it came straight from a restaurant kitchen.