If I have a lot of leaves, I arrange them in a single layer on a baking sheet, then bake in a 350F / 180C oven for about 5-7 minutes. Bake until dehydrated and crispy, but not browned.
If I have fewer leaves, or just don't feel like heating the oven, I'll throw them in a large skillet. Single layer if possible, over medium-low heat. Again, you want to barely toast them, not brown the leaves much.
Roughly 1 cup. But yield depends on the amount of leaves.