Place the gem squashes in a steamer over a pot of boiling water. Remove from the heat. Scope out the seeds with a spoon. Keep warm.

In the meantime, heat the oil in a small pot and sautée the onion, garlic mixture and curry powder until the onions are soft. Turn down the heat, add the chopped mushroom and keep stirring until they are cooked. Add tomatoes, then the creamed sweetcorn and seasoning salt, and heat through. Remove from heat.

Place the gem squash cut side up on a greased baking sheet lined with aluminium foil. Fill each hollow where the seeds were with as much of the sweetcorn/mushroom mix to the top. Divide the cheese among the six gem squash halves and sprinkle over the sweetcorn. Heat under a medium grill until the cheese begins to bubble. Remove from the oven and serve.