Heat oven to 425°. In a large bowl, combine tomatoes, sweet peppers, onion wedges and garlic. Add oil, salt and black pepper; toss to coat. Transfer mixture to a foil-lined shallow roasting pan.
Roast at 425° for 35 to 40 minutes or until vegetables are tender and slightly charred on the edges, stirring twice. Cool slightly on a wire rack. Lower oven temperature to 375°.
Transfer tomato mixture to a food processor. Cover and pulse with several on-off turns until mixture is chopped but still slightly chunky. Stir in balsamic vinegar and thyme.
Slice baguette crosswise into 1/4-inch-thick slices (about 36 slices). Lightly coat bread slices with nonstick cooking spray. Place on a baking sheet. Bake at 375° for 4 to 6 minutes or until golden and crisp, turning once. Cool on a wire rack.
Stir basil into tomato mixture. Top each bread slice with 1 tbsp of the mixture and some of the Parmesan.