Peel the onions and garlic, then chop them into small pieces. Melt some butter in a Dutch oven over medium heat (about 285°F/140°C) and cook the onions and garlic for 10 minutes, until the onions are golden. Meanwhile, wash the zucchini, cut it in half, and peel it if you like. Scoop out the inside.

Preheat your oven to 350°F (180°C). Add the crushed tomatoes and rice, then mix everything together. Simmer over medium heat (about 250°F/120°C) for 10 minutes, stirring regularly so it doesn’t stick. If your zucchini is too large for the dish, cut it into small cubes and add to the mixture to cook everything together. Transfer the mixture to a bowl.

Rinse the Dutch oven. Fill the zucchini halves with the stuffing, then place them back in the Dutch oven. Sprinkle the shredded cheese over the top. Remove any pot holders before placing the Dutch oven in the oven, and take off the lid if you want to bake uncovered. Bake for 25 to 30 minutes at 350°F (180°C), until the zucchini is tender and the cheese is golden on top.

Place on a serving dish and serve immediately.