Preheat the oven to 450 degrees F. Bring a 1/4 cup of water to boil in a large, wide skillet over medium-high heat. Add the spinach and cook until it just wilts and water evaporates. Add garlic and whipping cream and cook until cream lightly thickens. Season with salt, pepper and lemon juice, and then remove from heat. Place the oysters on a large baking sheet. Top each with a spoonful of spinach mixture, and then sprinkle with parmesan cheese. Bake for 10-12 minutes, until nicely browned and bubbling. Sprinkle with parsley and serve.