Preheat oven to 375 degrees. Toss grapes with 1 tablespoon of olive oil. Season with kosher salt and pepper. Spread on a baking sheet and roast for 25 minutes.
While the grapes roast, line the bread up on a baking sheet. Brush with remaining olive oil. Season with kosher salt and pepper. Bake along with the grapes until lightly toasted, about 8-10 minutes.
While the grapes finish roasting, add the ricotta to the food processor, pulse until whipped.
Let crostini cool, then spread with ricotta. Top with roasted grapes. Drizzle with truffle honey. Sprinkle with maldon salt.