Peel potatoes and chop into small pieces. Add to a saucepan filled with water and salt lightly. Bring to a boil and leave to cook while preparing the pie mix.
Pre-heat the oven to 200 degrees celsius.
Heat the olive oil in a large pot and throw in the diced onion and garlic. Cook on medium heat and stir regularly until the onion is translucent.
Add the soy mince to the pot, ensuring you break it with a wooden spoon. Drain the chickpeas and beans and toss both into the pot, as well.
Season the mince mixture liberally with dashes of Worcestershire sauce. Grind a few twists of black pepper and sprinkle a tablespoon or so of mixed herbs. Crush the vegetable bouillon cube and also add to the mixture.
Next, add the mushrooms, peas, sweetcorn and carrots. Turn the heat down a little bit and cover while the mushrooms release their juices, occassionally stirring to prevent the mixture sticking to the base of the pot. Leave this cooking until the potatoes have finished boiling, about 15min.
Once the potatoes are soft, drain and mash with a dash of oat milk.
Transfer the veggie mixture into a baking dish, leaving enough room for a layer of mashed potato. Generously sprinkle mozzarella cheese over the veggie mix, then distribute the mashed potato evenly over the top. Use a knife to spread the potato around to fill in any missing spots. Finally, sprinkle another layer of cheese over the top of the potato.