1. Preheat the oven to 350°F.
2. Spread walnut pieces over a baking sheet and toast until lightly browned, approximately 5 minutes.
3. Lower temperature to 325°F and place unwrapped brie in oven for 7 minutes, until warm.
4. In a large skillet heat oil and saute mushrooms and shallots with salt and pepper.
5. Cover and cook until softened, about 5 minutes, stirring occasionally.
6. Remove lid and cook additional 3 minutes until browned.
7. Add parsley and season with salt and pepper as needed.
8. Top brie with walnuts and mushrooms and serve with crostini, crackers and sliced French bread.