To prepare the peppers, slice the tops off and remove any veins or seeds inside. Do not discard tops as you will use any remaining pepper attached to the stem.
Add peppers to a casserole dish, fill with about 1/2 inch of water, cover with aluminum foil, and bake in a 425o F oven for 20 minutes in order to steam, or parbake, the peppers.
While the peppers are steaming, cook the quinoa in the chicken broth over high heat until fluffy, about 10 minutes. Remove from heat and stir in black beans, corn, zucchini, salsa, and salt and pepper.
Once peppers are done, remove from oven, discard water, and return peppers to casserole dish. Fill each pepper cavity with the quinoa filling until all of the peppers have been evenly filled. Top with pepper jack cheese and cojita, if using. If making ahead, store in airtight container in the refrigerator until ready to heat and serve.
Return peppers to oven and cook until heated through and cheese has melted. This should only take a few minutes.