1.Heat oil in a saute pan over medium heat. Add the onion, serrano pepper and cook about five minutes, until onion begins to brown. 2.Add garlic, spices and ground beef and mix well. 3.Once the beef begins to brown add the butternut squash and mix well. 4.Reduce the heat to medium low and cover with a lid for ten minutes until squash is tender and cooked through. 5.Remove the lid and add fresh sage. Stir gently to combine.