Stuffed Zucchini

Amazing vegetarian main dish or side dish.  In a saute pan, I added some olive oil and butter until hot, then added a finely chopped onion and let it saute until clear, then I added small chopped button mushrooms and let them saute until the juice came out, then I added some seeded, small chopped Roma tomatoes.  I let this mixture saute until tender.  While the mixture was sauteing, I halved and seeded 4 zucchinis.  I baked them while the mixture was sauteing until they were almost tender.  I added the mixture to the top of the zucchinis and topped with some Parmesan cheese and put them back in the oven for about 20 min at 350 deg.  These were amazing.  This could be stuffed with anything.