Preheat oven to 220°C/200°C fan-forced. Grease and line a large baking tray with baking paper. Place flatbread on tray. Drizzle with 1 tbs oil. Bake for 10 minutes.
Spread each flatbread with caramelised onion. Top with ham and brie. Bake for a further 10 minutes or until bases are crisp and brie has melted slightly.
Top flatbreads with rocket and thyme. Drizzle with remaining oil. Season with pepper. Serve.