Preheat the oven to 180 degrees C (350 degrees F). Prepare the bell peppers by cutting them vertically into clean halves, and scooping out the insides. Trim the stalks. Sprinkle some salt in the bell peppers and keep aside while you prepare the stuffing.
To prepare the stuffing, grind the cauliflower florets in a food processor, until they have broken down, into small granules.
In a pan, on the stove top, add some oil and heat it on medium heat. Add the ground cauliflower and the minced garlic. Cook this for around 5 minutes, stirring regularly, until the cauliflower releases its moisture and cooks down.
Add the diced mushrooms and combine, continue cooking for another 2 minutes.
Add the sweet corn, chopped parsley, oregano, onion powder, nutmeg powder, paprika, and combine well. Turn off the heat.
Add the grated cheddar cheese and salt, and mix together until the mixture is uniformly combined.
Using a spoon, stuff the insides of the bell peppers with the prepared mixture. Top the mixture with some mozzarella cheese, and brush the bell pepper with some olive oil.
To a baking pan, pour in some water. Place the bell peppers in the baking pan, leaving a little space between each pepper. Cover the dish loosely with aluminium foil.
Transfer the baking pan to the oven and bake for 35 minutes at 180 degrees C (350 degrees F) until the peppers are cooked and tender.