Heat the oven to 350°.
Cut the tops off of the peppers and clean out the seeds and membranes. (If the peppers won’t stand up, cut a little piece off the bottom to level.) Place the peppers on a baking sheet and drizzle with the oil.
Bake for 25 minutes, or until they start to soften. Remove from the oven and allow to cool.
Pour the oil from the peppers into a frying pan and add the onions, mushrooms, zucchini and oregano.
Season the vegetables with the salt and pepper, to taste, and sauté over high heat until they start to soften.
Add the tomatoes, rice, water and bouillon cube, and simmer for about 5 minutes. Adjust the seasoning.
Fold in the bacon, basil and mozzarella and divide among the peppers.
Sprinkle the Parmesan on top of the peppers and bake in the middle of the oven for 15 minutes, or until the cheese has melted and the filling is hot.