Begin by seasoning both the shrimp and salmon with Cajun seasoning. Ensure each piece is evenly coated for maximum flavor. Allow the seafood to sit for about 10 minutes while you prepare your cooking space with a large skillet ready on medium-high heat.

Heat a tablespoon of olive oil in the preheated skillet. Add the shrimp and salmon. Sear the shrimp for approximately 3-4 minutes per side until they turn pink and slightly crispy, while cooking the salmon skin-side down for about 4-5 minutes until golden and opaque. Flip gently to avoid breaking the salmon.

Remove the cooked seafood from the skillet and set aside. In the same skillet, add minced garlic and sauté for about 1 minute until fragrant. Gradually pour in heavy cream, stirring constantly, and let the mixture simmer for 3-5 minutes until it thickens slightly. Season with salt and pepper to taste.

While the sauce simmers, prepare the mashed potatoes by boiling peeled and cubed potatoes in salted water for 15-20 minutes until tender. Drain, then mash with butter, cream, salt, and pepper until creamy and smooth.

In a small pot of boiling water, quickly blanch the green beans for about 3 minutes until bright green and tender-crisp. Transfer them to an ice bath to halt the cooking process and maintain vibrant color. Drain and set aside.

Assemble the dish by creating a bed of buttery mashed potatoes on each plate. Arrange the shrimp and salmon on top, drizzled with the garlic cream sauce, and add a handful of blanched green beans on the side.