Heat a gas grill fitted with a wood chip tray or smoker box on high.
Place the cut tomatoes in a large bowl. In a separate bowl, whisk together the olive oil, balsamic vinegar, herbs, salt, and pepper. Drizzle the dressing over the tomatoes, gently tossing them to coat evenly.
Place the tomatoes cut side up on a baking sheet lined with foil, and place the baking sheet on the grill grates. Close the cover and roast the tomatoes for 20 to 30 minutes. They should be very soft and starting to char.
Place the tomatoes back in the large bowl and cool
To make the garlic toast, mix the butter, garlic, and parsley together in a small bowl. Spread mixture evenly over the baguette halves. Place the bread, cut side down, directly onto the grill grates, and cook until it is toasted and beginning to char.
Turn the bread and sprinkle the cut halves with the Parmesan cheese. Cook, covered, for another 2 to 3 minutes, or until the bread begins to turn golden brown and the cheese begins to bubble. Watch the bread carefully to prevent burning. Remove the bread to a cutting board and cut each half into 2 pieces.
Spoon the soft, grilled tomatoes onto the baguettes, season with salt and pepper if desired, and serve immediately.