Can I cook lamb in an electric toaster oven?

The model you name calls itself "roaster oven" so I don't see why not.
The main difference from a regular oven is that with a closed appliance, braising is probably your main or only choice of method.
Follow directions/guidelines of your machine.
Cut meat (as needed) to fit.
Many recipes for rack, leg or chops here on food52 and other sites.
One classic prep is with rosemary. Another unusual one is with pomegranate flavoring.
Good luck with your meal and please tell us what you decide to do.