My husband actually had the idea for these!  Thanks RyGuy!
My diet is starting to get a little tighter, but that doesn't mean we can't get creative for our dinners still.   
I'd say this one is a keeper, with a few minor changes.

1lb lean ground beef (or ground turkey breast)
1 cup jarred marinara sauce
3 medium to large green bell peppers (or red, yellow, or orange)
2 medium tomatoes
2 ounces shredded mozzarella cheese
salt and pepper
parmesan cheese (optional)

Preheat oven to 375. Brown beef in large skillet over medium high heat.  While that is browning, cut peppers in half, lengthwise, pull out ribs and seeds, and cut off stems.  

When the beef is browned, turn the heat down a bit, and add marinara sauce.  Stir to combine and cook on medium low for about 5-10 minutes.  While that is cooking, slice up two tomatoes, you should get 3 1/4inch slices from each tomato.  
Place peppers on baking sheet, fill peppers with beef marinara mixture, top each pepper with a tomato slice, sprinkle with salt and pepper, and place in oven for about 25-30 minutes.  

Pull peppers out, top with mozzarella cheese and bake for another 10-15 minutes.  I like to broil them at the very end to brown the cheese.  
I baked these for only 30minutes total and the papers were still a little crunchy, so I would definitely recommend 45minutes total.  
I diced up the ends of the tomatoes for a side salad.  

You can substitute jarred pizza sauce for marinara if you prefer.  Other yummy add ins are sliced black olives, pepperoni, and mushrooms.