While the squash is roasting, make the filling. Heat a large saute pan to medium-high heat. Drizzle with olive oil or vegetable and add the ground beef. Break up beef with a spatula and cook until browned. Removed browned, crumbled beef from the skillet and set aside. Depending on the amount of fat left in the pan, you can drain some of the fat or add more oil if needed. Add the onions, pepper, and jalepeno to the pan.