BGE Europe:250 to 275 °C for 30 minutes, not above 275 °C; 200 °C for 15 minutes for excess smoke; keep cooking below 300 °C. The most specific and most recent, and this guide's line.
BGE UK (Alfresco Concepts): a "carbon clean" at 300 °C for 15 to 20 minutes. Its gasket is rated to 500 °C.
BGE US: rates the EGG to 399 °C (750 °F) and says "high heat" for about 20 minutes. That is the cooking range, not clean-burn advice.
Over-firing: flames spilling from the top or round the gasket mean it is too hot (every manual). Close both vents. Owners link "nuclear" clean burns to cracked fire boxes (owner report).