KasaBona 12 Hole Mince Pie Baking Tray. KasaBona Baking Tray Bunseet it is made of heavy duty carbon steel, this mince pie baking tray resists rust and warping, and is oven safe to 220°C. DURABLE MATERIALS: made of heavy duty carbon steel, this mince pie baking tray resists rust and warping, and is oven safe to 220°C.