Preheat oven to 350 F. Grease an 11" fluted quiche dish or a deep-dish pie plate well.
Heat the ghee in a skillet over medium-low heat and cook the onions, seasoned lightly with salt and stirring frequently, until golden-brown and caramelized, 20 to 30 minutes. Stir in the sage and allow the onions to cool slightly. Spread the onions evenly over the bottom of the prepared quiche dish or pie plate.
Add the roasted pumpkin, coconut milk, water, eggs, salt and pepper to the bowl of a food processor or blender and puree until smooth. Pour the pumpkin mixture over the onions in the prepared dish.
Bake the pie for 40 to 50 minutes, or until a knife inserted in the center comes out clean. Cool for at least 15 minutes before serving.