Begin by making the glaze in a pot. In a medium sauce pot on a medium flame, add piloncillo, sugar, and the water. It should take about 10 minutes for the sugar to dissolve. Add canela and orange juice, cook for another 10 minutes and then begin to whisk in butter. Place quartered pumpkins on a sheet tray, and pour spoonfuls of glaze on each piece. In a preheated 400-degree oven, cook calabaza for 20 minutes until roasted through.