Preheat the oven to 450°F. Place the grapes on a large sheet pan and drizzle with olive oil. Sprinkle with salt, pepper, and rosemary leaves then toss to coat, spreading them out in an even layer. Roast in the oven for 10 minutes, then set aside to cool.
While the grapes are roasting, make the whipped goat cheese spread. Add all ingredients to a food processor and process until smooth and creamy, scraping down the sides a couple of times. Or, use an electric hand blender to whisk in a bowl.
Heat your grill or a grill pan over medium-high heat and brush grates or pan with olive oil. Liberally brush both sides of the baguette rounds with olive oil. Once the grill or pan is hot, add the baguette rounds and grill each side until light grill marks appear (you may need to do this in batches).
Spread 1-2 tablespoons of the whipped goat cheese on top of each baguette round. Spoon a few grapes and some of their juices on top, followed by a pinch of flaky sea salt, a few sprigs of rosemary leaves, and a drizzle of hot honey. Serve warm or at room temperature.