If you don't have cooked rice, make some (this step can be done a day or two ahead). I usually just do 1/2 cup uncooked rice which ends up making a bit more than you need for this recipe, and then I use the rest for other things.
Preheat your oven to 400F and move the rack to the middle position. Meanwhile, prep your ingredients. Cut the tops off the peppers as if you were carving a pumpkin (try to do it as evenly as possible so the filling doesn't fall out). Remove any seeds. Chop up the usable stuff from the pepper tops (we will add it to the filling).
Place the peppers cut-side up in a baking dish (I used a 9x13 one). Pour one cup of water into the bottom of the dish (this will help the peppers steam to cook them faster).
Add the oil, onion, and chopped up pepper tops to a skillet. Sauté over medium-high heat for 5 minutes.
Add the beef, smoked paprika, garlic powder, cumin, and chili powder to the skillet. Cook it until it's browned and cooked though (approx. 8 minutes), stirring occasionally and breaking the beef up with the spoon as you go along. I use the leanest ground beef I can find so I don't need to drain the fat. If yours is fattier, spoon out some of the fat.
Once the beef is done and most of the liquid has been cooked off, take it off the heat. Add salt & pepper to taste. Stir in the cooked rice, the entire jar of salsa, and 1/2 of the cheese. Spoon the mixture equally into each pepper.
Cover the baking dish with foil. Place it in the oven and bake for 40 minutes.
Take the dish out of the oven. The peppers should be still a little bit firm to the touch (we don't want everything collapsing). Sprinkle the remaining cheese over top. Return the peppers to the oven for another 5-10 minutes or until the cheese is melted.
Serve immediately. I like to sprinkle a little cilantro over top.