Preheat your oven to 400°F (200°C). Rinse the grapes thoroughly under cool running water and remove them from their stems. Pat them dry with a clean kitchen towel. Choose firm, ripe grapes for the best balance of sweetness and texture.
Place the grapes in a mixing bowl. Add olive oil, balsamic vinegar, chopped rosemary, thyme if using, black pepper, and a small pinch of salt. Add honey if you prefer a slightly sweeter finish. Toss gently until the grapes are evenly coated.
Spread the seasoned grapes in a single layer on a parchment-lined baking sheet or in a shallow ovenproof dish. Leave a little space between the clusters so the grapes roast evenly rather than steam excessively.
Roast for 20–25 minutes, gently shaking the pan once halfway through. The grapes should become soft, slightly wrinkled, and juicy, with some of their natural juices mixing with the balsamic vinegar. Roast for a few additional minutes if you prefer a more concentrated flavor, watching carefully to prevent burning.
Remove the grapes from the oven and allow them to rest for a few minutes. Spoon the grapes and their flavorful juices into a serving dish. Garnish with fresh herbs, goat cheese, or toasted nuts if desired. Serve warm with crusty bread, cheese, or a fresh salad.