Step 1

Preheat the oven to 375 degrees F (190 degrees C).

Step 2

Heat a skillet over medium heat. Add cauliflower rice and saute until heated through, about 5 minutes. Set aside.

Step 3

Heat oil in another skillet over medium-low heat. Saute onion and garlic in the hot oil until soft, about 5 minutes. Add ground beef and cook until browned, breaking it up into small pieces, 5 to 7 minutes.

Step 4

While the meat cooks, trim tops off bell peppers and hollow out. Use a knife to level off the bottoms of any bell peppers that don't stand mostly upright. Take care not to create a hole in the bottom (if it happens, just fill the pepper with loads of cheese before adding the meat mixture). You can also simply slice the peppers in half lengthwise, leaving the stem on.

Step 5

Stir cauliflower rice, tomatoes, 1/2 cup Parmesan cheese, tomato sauce, and parsley into the beef mixture and cook 2 to 3 minutes more. Season to your liking with salt and pepper.

Step 6

Divide filling evenly among bell peppers and nestle them in a baking pan or line on a sheet pan. Top with remaining Parmesan.

Step 7

Roast in the preheated oven until peppers are soft, 25 to 35 minutes.