Take the brie out of the refrigerator prior to serving so it can come to room temperature.
Preheat the oven to 400 degrees.
Place the slices of bread onto a baking sheet, coat with olive oil spray if desired. Bake in the oven for 2-3 minutes, or until crisp and golden brown.
Place the room temperature Brie onto a plate and serve with the crostini and grapes. Enjoy. Side Note: If you prefer melted Brie, simply place the Brie onto the plate, cook in the microwave for 30-45 seconds then add the crostini and grapes.