First prepare the butternut squash, cut the top long neck off leaving the round small base. Remove the pips and clean out. Peel two of the necks and cut into 1cm dice, reserve the other two butternut squash for something else.
In a large frying pan add some olive oil and gently sauté the squash, this should take about 20 mins. Remove put onto a plate while you cook the rest of the mixture.
In the same frying pan put in the butter and place onto a medium heat add the onion and cook until soft, add the mushrooms turn up the heat for a couple of minutes make sure they are cooked.
Now add the garlic and sundried tomatoes and pine nuts and mixed herbs and the saved cooked squash, mix well and put into a bowl to one side.
Make sure each base sits nicely in the gratin dish. Now fill the four squash to the top.
Meanwhile In the same frying pan soften the onion, put into a bowl and add all other ingredients, mix well and season. Cover each squash with some mixture and place into a gratin dish put into the oven for 25 minutes at 180°C. Serve.