Kale/Collard chips are yummy, and more popular than many other ways to prepare green leaves. I've made them a few times, and this is what I've come up with. It's easy to have too much oil on the leaves. The best way I've found to prepare the leaves is to first remove the center ribs, cutting the leaves in half, and stack them up in the biggest bowl I have.
Then I dribble olive oil on the pile and start rubbing it onto the leaves--like applying lotion, really. Then I sprinkle with salt and rub around some more (I've also had issues with too much salt, but no salt is not popular). Some recipes use a spice mix in addition to salt, and that's very nice. You want your spices finely ground. Then I lay them out on cooling racks in baking pans in a single layer (you could probably get by without the rack, but you might have to go in and turn them over halfway through).
I put the leaves into the
oven at 225 degrees Fahrenheit, but I've seen all sorts of temperatures for doing this. I figure a lower temperature preserves more nutrients. I'm lucky in that I have a convection oven, so I have it set to "convection roast" and it blows hot air over and under the leaves so I don't have to turn them. I've heard of making kale chips in a dehydrator, but I haven't tried it.