Preheat oven to 400 F and line 3 baking sheets with parchment paper.
To make crostini, in a medium bowl, toss baguette slices with olive oil and rosemary. Place on baking sheet and bake until slightly golden and crisp, turning once for even baking on both sides, about 7-10 minutes. Remove from oven and let stand until ready to serve.
Reduce oven to 350 F.
Place grapes on a baking sheet and drizzle with olive oil, balsamic vinegar and rosemary.
On the last baking sheet, place brie wheel. Place both baking sheets in the oven and bake for 15 -20 minutes or until brie has softened and grapes have caramelized.
Remove from oven and carefully transfer brie to serving plate. Top brie with roasted grapes and drizzle grapes with their juices. Season grapes with salt and pepper.
Serve with crostini and your favourite crackers.