Heat up 1 tbsp vegetable oil in a large deep frying pan over high heat until it begins to smoke. Add in all 1lb/500g of your veg and begin to stir fry. Shake the pan frequently so the veg doesn't steam itself, you want the veg nicely browned and still a little firm. The veg will cook through properly as you simmer the sauce and bake in the oven, so don't worry too much if it's browned but not completely cooked through.
Add 1 tsp garlic and a pinch of salt and pepper, continue stir frying for another 1-2mins until the garlic browns.
Turn heat down to medium and stir in 2 tbsp tomato puree. Fry the puree for 1-2mins, then add 3x 14oz/400g cans of chopped tomatoes. Add a drizzle of water to the cans and shake out all the tomato juice.
Pour in 1cup/250ml vegetable stock, then add 1 heaped tsp oregano & basil, 1/2 tsp sugar and chilli flakes (or to taste) and salt & pepper (to taste). Give it a good stir then simmer for 15mins, or until it starts to thicken slightly.
Meanwhile, add 10.5oz/300g pasta to salted boiling water and boil until al dente. You want it still a bit hard otherwise it'll go soft and mushy in the oven. Drain and combine with sauce. Preheat oven to 200C/390F.
In a suitably sized baking dish, spoon in half your pasta, top with 1cup/100g mozzarella, spoon over the rest of your pasta and top with cheddar (to you hearts content). Bake in the oven for 20mins or until golden and bubbly on top.
Allow to cool for a few mins then serve with an extra helping of fresh parsley!