Pat the large sea scallops completely dry using paper towels to ensure a perfect sear. Remove the side muscle if attached, then generously season each scallop with salt, freshly cracked black pepper, and Cajun seasoning. Set aside.

Place a cast iron or stainless steel skillet over medium-high heat for 2-3 minutes until hot. Add olive oil and butter, swirling until melted and foamy.

Carefully place the seasoned scallops in the skillet, ensuring they are spaced apart. Sear for 1.5 to 2 minutes on one side until golden crust forms. Flip and sear for another 1.5 to 2 minutes until fully cooked. Remove and set aside.

Lower the heat to medium and add unsalted butter. Once melted, add minced garlic and chopped shallot. Sauté for 2-3 minutes until shallots are soft and golden.

Stir in Cajun seasoning, smoked paprika, and optional red pepper flakes. Cook for 1 minute, allowing the spices to bloom.

Deglaze the pan by pouring in the chicken or seafood broth, scraping up brown bits. Simmer for 1 minute to reduce slightly.

Slowly pour in heavy cream, stirring well. Add grated Parmesan and lemon juice, stirring until cheese melts and sauce thickens. Simmer for 3-4 minutes.

Return the seared scallops to the skillet, gently tossing in the sauce for 1-2 minutes. Garnish with freshly chopped parsley and serve immediately.