To prepare the 6 bell 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 425°F oven for 20 minutes in order to steam, or parbake, the peppers.
While the peppers are steaming, cook the 1 pound ground beef, 1 yellow onion, 2 cloves garlic, and any remaining pepper from the stem piece (diced) in a large sauté pan over medium high heat until the meat is crumbly, about 10-15 minutes. Add 1 zucchini(diced) and allow to cook for 1-2 minutes. Remove from heat and add the par cooked 2 cups rice (frozen microwavable rice works best) and 15 ounces diced tomatoes. Add about 1/4 teaspoon salt to taste.
Once peppers are done, remove from oven, discard water, and return peppers to casserole dish. Fill each pepper cavity with the ground beef and rice filling until all of the peppers have been evenly filled. Top with pepper 8 ounces pepper jack cheese. 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.
Video
Notes
Cooking tips:
You can use any kind of bell peppers when you make stuffed peppers. I'm partial to the red, orange, and yellow ones.
Since the filling is often already cooked when you stuff them into the pepper cavity, it is important to par bake the peppers so that they are evenly cooked with their stuffed ingredients. To do this you can roast in a covered pot in the oven like I did, blanch the peppers in boiling water and then transfer them to an ice bath, or you can even steam them in the microwave in a covered dish with a bit of water.
To make this recipe easier, buy frozen pre-cooked rice that only needs to be heated prior to eating.
Grated cheese from a block always melts better than pre-shredded cheese, but you can use either.