Oysters Rockefeller - cooking recipe

Ingredients

12 large oysters
1 tablespoon fresh lemon juice
1 tablespoon butter
1/4 teaspoon sea salt
1/4 teaspoon black pepper
1/2 cup pickling salt (coarse)
1 tablespoon butter
1/4 cup celery, finely chopped
1 large garlic clove, pressed
1 1/2 tablespoons parsley, chopped
0.5 (150 g) package frozen spinach, thawed
1/2 teaspoon black pepper (or to taste)
3 tablespoons heavy cream
125 g brie cheese
1 teaspoon hot sauce (or more to taste)
2 tablespoons panko breadcrumbs, divided
1/3 cup grana padano, grated (or as needed)

Preparation

Shock oysters and, with its liquor, put in a small pot. Rinse bottom shells and place them upside down on paper towel; set aside. Add lemon juice, butter, salt and pepper. Cover and cook for 3 minutes on medium-low. Drain oysters and reserve. On a baking sheet, spread coarse pickling salt to cover the surface, about 1/4\" thick. Place shells on salt and set aside.
In a medium pot over medium-low heat, melt butter. Add celery, garlic and parsley. Cover and cook for 3 minutes at medium-low. Add spinach and season well with pepper. Increase heat to medium, cover and cook 2 minutes. Add cream, cheese (Brie), hot sauce and 1 tablespoons bread crumbs. Mix and cook for 2 minutes; stir constantly. If more cream is needed, add some.
Place oysters in their shell. Cover with spinach mix and sprinkle with remaining bread crumbs and Grana Padano. Cook under broil for 3-4 minutes.