The cooker may be rated at 5.5kW, but the principle is that every bit
of cable must be protected by a fuse or breaker that prevents it being
overloaded (and that protection must be on the supply end!) If the
cooker develops a fault that causes it to draw 44A the breaker on your
45A circuit will be perfectly happy - however the 2.5mm T&E will be no
more than a memory and a paragraph in the fire brigade's incident
report.