If frozen, thaw puff pastry according to package directions (note that the kind that isn't rolled out usually requires thawing overnight unless you want to thaw it in the microwave).
Pre-heat oven to 400F. Move the rack to the middle position. Line a baking sheet with parchment paper.
Place tomatoes in a baking dish and toss with about a tablespoon of olive oil. Sprinkle with some garlic powder, fresh thyme (take the leaves off the stems), herbs de Provence, and salt & pepper. Roast tomatoes for 20 minutes.
Meanwhile, make the balsamic drizzle by combining the balsamic vinegar and brown sugar in a small pan. Cook on medium heat until it’s reduced by half (about 10 min.).
If your puff pastry isn't rolled out, roll it out on a lightly floured surface into a sheet that's about 12 inches long (it should comfortably fit on the baking sheet).
When the tomatoes are almost done, place the puff pastry on the baking sheet. Spread the tomatoes (and the leftover oil/juice) onto the pastry. Bake for 15-20 minutes, or until the pastry is cooked and lightly browned.
Cut into squares (I used a pizza cutter!), use a spoon to drizzle the balsamic reduction on each piece, and serve immediately.