Snap off ends from asparagus and peel any tough skin from the stalks; set aside.
In 3-quart saucepan, heat oil and 1 tablespoon unsalted butter over medium-high heat until hot. Add garlic to oil and butter; cook until light brown. Add onion and celery; reduce heat to medium and cook 10 minutes, stirring occasionally, until vegetables are tender.
Meanwhile, make the gremolata. In 8-inch skillet, melt 2 tablespoons butter over medium heat. Add bread crumbs to butter; cook until lightly browned, stirring frequently; transfer to small bowl. Stir in the parsley and orange peel; set aside.
In saucepan, add asparagus, broth and thyme to vegetable mixture. Heat to boiling; cook about 3 minutes or until asparagus is tender. Stir in spinach and lemon peel (the spinach will wilt in the soup). Pour soup into blender in small batches; cover and puree each batch until smooth. (The soup can be made ahead to this point, cooled, covered, and refrigerated for up to 1 day or frozen for up to 1 month.)
Return soup to saucepan and heat over low heat until hot. Stir in the whipping cream, salt and pepper. Ladle into warm bowls. Sprinkle soup with 1 teaspoon gremolata. Pass the remaining gremolata at the table.
Set oven control to broil. To make bruschetta, butter bread slices on both sides and top each with several slices of brie (2 to 3 oz per bread slice). Broil with tops about 5 inches from heat until cheese is bubbly and slightly browned.