Cook and stir the beef mince in a frypan over medium heat until brown and crumbly, breaking the meat apart as it cooks, about 10 minutes. Drain off excess grease. Set the beef aside.
Preheat oven to 200 degrees C. Spread the bottom of a 20x30cm baking dish with about 1 teaspoon of olive oil.
Pour the remaining olive oil into a large frypan over medium-high heat and cook and stir the zucchini, red capsicum, green chilli, garlic and the white parts of the spring onions until the vegetables begin to soften, 3 to 5 minutes. Sprinkle with salt and black pepper and mix in the tomato paste, chilli powder and cumin. Allow the mixture to simmer until the spices are fragrant, about 1 minute. Remove from heat.
Stir in the browned beef mince, black beans, kidney beans, corn and 1/4 cup of Parmesan cheese until well combined. Adjust salt and pepper if necessary and spread the mixture into the prepared baking dish. Top with remaining 1/4 cup of Parmesan cheese and cover the dish with foil.
Bake in the preheated oven until bubbling in the centre, 20 to 25 minutes; remove the foil, return to oven and bake until the cheese is browned, 5 to 10 more minutes. Sprinkle the remaining spring onions (green tops) and coriander over the top.