Wash the squash and cut it in half lengthwise. Carefully remove the flesh of the squash making sure to leave a border of around 1 cm (to tender both the skin and the flesh you can microwave each half for a few seconds).
In a bowl combine the cous cous, the onion, the tomato and the squash pulp all finely cubed), the borlotti beans with their juice, a splash of oil, then the spices and the stock powder. Mix well then add around ½ cup of water.
Arrange the squash cases in a tray, season with salt and pepper and another touch of oil.
Stuff with the filling trying to include all or pretty much all the liquid (this will allow the couscous to cook properly). Drizzle with the remaining oil.
Bake in a preheated oven for 45 minutes at 180°. If it becames too dark after the first 20 minutes, cover with foil.
Serve both hot or cool/at room temperature.