Begin by patting the shrimp and salmon dry with paper towels. Generously season both the shrimp and salmon with Cajun seasoning, ensuring an even coating on all sides.

Heat a large skillet over medium-high heat and add a drizzle of olive oil. Once hot, add the seasoned shrimp to the pan in a single layer. Sauté the shrimp for about 2-3 minutes per side, or until they turn a vibrant pink and curl slightly. Remove the shrimp from the skillet and set aside.

In the same skillet, reduce the heat to medium. Place the salmon fillets skin-side down into the skillet. Cook for about 4-5 minutes without moving them, allowing a crisp crust to form. Carefully flip the salmon and cook for an additional 4-5 minutes, or until the fish flakes easily. Remove the salmon and keep warm.

Reduce the skillet heat to low and add a tablespoon of butter along with minced garlic. Sauté the garlic for about 1-2 minutes, or until fragrant but not browned. Pour in the heavy cream, stirring continuously for approximately 3-5 minutes, until the sauce thickens slightly.

While the sauce is cooking, bring a pot of water to a boil and add peeled, cubed potatoes. Boil for about 15-20 minutes until they are fork-tender. Drain the potatoes, then return them to the pot. Mash them with a generous pat of butter and season with salt and pepper to taste.

In another pot, bring water to a rapid boil and add trimmed green beans. Blanch the green beans for about 3-4 minutes, or until they are tender-crisp and vibrant green. Once cooked, drain and toss them with a pat of butter and a sprinkle of salt.

To serve, plate the salmon and shrimp, generously drizzling the creamy sauce over the top. Arrange the buttery mashed potatoes and crisp green beans alongside.