Hi Pete,
If you cook something like that, you use an oven bag, if you made a real mess in there it’d be impossible to get clean.
For normal stuff, I occasionally use a gel based oven cleaner, avoiding any holes and the wave guide cover. Then it all just wipes out easily.
I use mine for small stuff, taco shells, cakes, vegetable/pasta bakes, anything where fat isn’t the base.
The big oven is for anything really messy.
Cheers
Nathan