Heat 3 tbsp olive oil in a large frying pan, add the onions and garlic and cook until beginning to caramelise, about 10 minutes. Add the spices and cook for two minutes more. Add the lentils, reserved squash and 300ml of hot water and simmer for 8 minutes (until most of the water has been absorbed). Remove from the heat and stir through the feta, pine nuts, herbs and lemon juice. season to taste with salt and pepper. (again the filling could be made ahead of time and the squash re-heated as required).