As a South African expat I grew up with gem squash as being the one and only squash we ever saw at our table.
We ate them cut in half with their hard outer skin serving as a bowl. Filled with lots of butter and sometimes tender green peas they were delicious.
I grew some here for seed and gave a couple to a friend.
She pricked it with lots of holes and put it in her microwave. After a few minutes the door blew open and she had squash splattered all over her kitchen. To be safe please cut your gems in half before cooking.
There is a nice article about gem squash and how to grow them.