Preheat oven to 400°F
Wash peppers, then cut 4 peppers in half lengthwise and discard seeds
Lay cut-side up in lightly oiled baking dish, season with salt and pepper
Bake 15-20 minutes until tender
Heat 1 tsp oil in skillet over medium-high heat
Add all the beef to pan, break into large chunks and sear undisturbed 4-5 minutes
Flip meat over, season with salt and pepper, then break into small pieces
Cook 3-5 minutes until fully cooked with no pinkness remaining
Remove from heat and mix in 1 cup sauce
Divide meat mixture among peppers and top each with 1-2 tbsp cheese
Bake 15-20 minutes more or until hot and melty