Prepare the reduction

1. Pour balsamic vinegar and honey into a saucepan and add rosemary. Bring to a boil, then turn down.
2. Start checking at 5 minutes. Keep in mind, it will thicken as it cools. Reduction is ready as soon as it coats the back of a spoon.

Roast Grapes

1. Preheat oven to 400 to roast grapes.
2. Toss the grapes in olive oil and a little salt and pepper.
3. Cover a sheet pan with parchment paper and pour grapes into the pan.
4. Roast for 15-30 minutes, until the grapes are wrinkly and have a few dark, caramelized spots (especially on the bottom). Leave the oven on.

Assemble Dish

1. Place brie on parchment paper in the middle of the pan
2. Warm brie for 10-15 minutes in the same oven. Test by pushing on the center of the brie. Should feel very soft, like almost liquid. Since you'll be covering the brie with grapes, you could also take a very long skewer and check if the middle is hot and gooey.
3. Place brie on a serving platter with room for it to ooze out once cut.
4. Top brie with grapes, balsamic reduction, and more honey, if desired. Garnish with rosemary.