Wash and slice each zucchini lengthwise. Scrap flesh out and reserve as you will add this to the meat mixture once cooked.
Set oven to bake at 375F. Place zucchini cut side up on parchment or Silpat lined baking sheet, rub with oil and season with salt and pepper. Bake for 15 minutes. I like my zucchini tender crisp, so if you like them softer, add another 5 minutes.
Brown meat, then add onion and garlic and cook until onion is translucent. Add salt, pepper, chili powder, cumin, reserved zucchini flesh, tomatoes, corn and black beans. Cook until most of the liquid is absorbed.
Next, remove zucchini from oven and fill the boats with the meat mixture. Pile it high and top with cheese if desired. I usually have some meat mixture left over and use it to either eat along side the boat, or in another dish like taco salad.
Cook zucchinis for an additional 10 minutes or until cheese is melted. I usually broil the last 2 minutes.
Top with green onion, cilantro and sour cream (or my tahini dressing that I tagged in the Plant-Based Meal Prep Bowl above!)