In a bowl combine champagne, spinach, onions, 1/4 cup of the breadcrumbs, and parsley.
In a skillet, melt butter over medium heat. Add champagne-breadcrumb mixture. Cook 1-2 minutes, sitrring until spinach is wilted. Spinkle with salt and pepper to taste. Remove from heat.
Place oysters in the shell on a baking sheet. Put 1 tablespoon of champagne-breadcrumb mixture on each oyster. Spinkle remaining breadcrumbs and Parmesan cheese on top of oysters.
Place baking sheet on the barbecue grill. Grill for about 5 minutes, with the lid closed, or until cheese is bubbling and is starting to brown.
Cover the bottom of a shallow serving platter with a layer of kosher salt.
Remove oysters from baking sheet. Place oysters on the salted shallow serving platter. Garnish with lemon wedges and/or parsley.