Preheat your oven to 400°F (200°C). On a parchment-lined baking sheet, toss the grapes with 1 1/2 tablespoons of olive oil, the balsamic vinegar, salt, and pepper. Spread them in an even layer and roast for 20-25 minutes, or until the grapes are soft, caramelized, and their skins begin to pop. Set aside to cool slightly.
While the grapes are roasting, combine the ricotta cheese and lemon zest in a small bowl. Season with a pinch of salt and pepper, and stir until smooth and well combined. For an extra creamy texture, you can whip the mixture using a hand mixer for 1 minute.
Decrease the oven temperature to 375°F (190°C). Arrange the baguette slices on a separate baking sheet and brush lightly with olive oil on both sides. Bake for 8-10 minutes until golden brown and crisp.
Spread a generous amount of the lemon ricotta mixture onto each toasted baguette slice. Top with a few of the warm roasted grapes and their juices. Finish with a drizzle of honey, an optional sprinkle of fresh thyme leaves, and flaky sea salt and cracked black pepper if desired. Serve immediately.