In the work bowl of a food processor, pulse spinach, in batches, until finely chopped. In a large skillet, heat oil over medium-high heat. Add garlic; cook until lightly browned, about 1 minute. Gradually add spinach; cook until wilted, about 5 minutes. Remove from heat. Stir in cream, liqueur, 1/4 tsp. salt, and 1/4 tsp. pepper.
Preheat oven to 400°.
Remove oysters from shells, reserving oysters. On a rimmed baking sheet, add kosher salt. Add oyster shells, and fill shells with spinach mixture. Top with cheese and bread crumbs. Bake until lightly browned, 8 to 10 minutes.
In a shallow dish, add buttermilk. In separate dish, whisk together cornmeal, flour, cayenne, remaining 1 1/2 tsp. salt, and 1/4 tsp. black pepper. In a Dutch oven, pour oil to a depth of 2 inches, and heat over medium-high heat until a deep-fry thermometer registers 360°.
Dip oysters in buttermilk, letting excess drip off. Dredge oysters in cornmeal mixture, shaking off excess. Carefully place oysters into hot oil in batches. Cook until golden brown, 2 to 3 minutes. Drain on paper towels. Serve over spinach mixture, and sprinkle with additional salt, if desired. Serve with lemon wedges.

*Notes We used Pernod