Pat scallops thoroughly dry with paper towels to ensure a proper sear.
Season both sides of the scallops with Cajun seasoning and salt.
Heat grapeseed oil in a large stainless steel or cast iron skillet over high heat until just smoking.
Place scallops in the pan, ensuring they do not touch, and sear for 2 minutes until a deep golden crust forms.
Flip the scallops and sear for an additional 1 to 2 minutes; remove from pan and set aside.
Reduce heat to medium, add butter to the pan, and sauté shallots and garlic for 1 minute until fragrant.
Deglaze the pan with white wine, scraping up any browned bits from the bottom.
Whisk in the heavy cream and simmer for 3 minutes until the sauce thickens slightly.
Stir in lemon juice and return scallops to the pan briefly to coat in sauce.
Garnish with fresh parsley and serve immediately.