Sounds like you need that knife to halve 'em, then a spoon to dig out the pulp.
I remember really liking the cactus-fruit jam as a kid, when we came home from Carlsbad Caverns having picked up a jarful in the gift shop. Haven't had any since. Wonder if you can google up a good recipe -- we have plenty of prickly pear growing wild and in gardens around here. There's this huge patch at the foot of the Conejo Grade...
Yep, you can. This one's simple.
Okay, pilgrim, if you've got any saguaro cactuses in your neighborhood,
this recipe ought to come in really handy.
And one more, very like the first. Some more hints on removing the little spinies.