Preheat the oven to 180 (fan). Heat up the oil in a saucepan and add the onions and celery. Cook over a medium heat until becoming translucent and softened then add the minced garlic and dried herbs plus the spices. Fry for a few seconds until fragrant. Add the tomato paste and stir until every in the pan is coated. Add the tinned tomatoes and season well with salt and pepper. Fill the empty tomato tin up a quarter with water, swill out and add that into the pan also.

Bring to a simmer and cook gently for around 10-12 minutes to allow the flavours to infuse together. Remove from the heat.

Season the sliced courgettes with salt and pepper then layer the sliced courgettes in an oven proof dish until they cover the base then spoon over some of the tomato sauce. Layer more courgettes, then again more sauce. Repeat this process until all the courgettes and sauce are gone.