Combine breadcrumbs and cheese in a small bowl; set aside.
Spread butter on 1 side of each bread slice. Combine 1/8 teaspoon salt and black pepper; sprinkle over butter. Place bread slices, buttered side up, on a baking sheet. Bake at 350º for 15 minutes or until lightly browned and crisp. Set aside.
Combine cream and shallot in a 10-inch, ovenproof skillet; bring to a boil over medium-high heat, stirring often. Cook 15 minutes or until reduced to 1 cup, stirring often. Stir in remaining 1/8 teaspoon salt, chopped rosemary, and white pepper. Add oysters; cook 1 minute or until edges of oysters begin to curl. Remove from heat. Sprinkle with breadcrumb mixture. Broil 3 inches from heat 2 to 3 minutes or until golden brown.
To serve, spear a rosemary sprig through each toasted bread slice; place a bread slice in each of 4 individual shallow bowls. Spoon oyster mixture around bread. Sprinkle with parsley. Serve immediately.