Place acorn squash halves cut side down in a baking dish with 1/4 inch water. Cover with foil and bake 40-50 minutes or until tender.
While the squash is roasting, prepare the picadillo filling (this can also be made the day before):Place olive oil in large skillet over medium heat. Sauté onions, green pepper, and garlic for 5 minutes or until tender.
Add cumin and oregano and sauté another 1-2 minutes. Add ground beef, turkey, or chicken and cook together with vegetables for 10 minutes or until lightly browned and cooked through.
Add tomato paste, sherry, water, sliced olives, Worcestershire sauce, and Tabasco to mixture. Combine well and cook for 10 minutes. Add salt to taste.
Remove acorn squash halves from oven and fill with picadillo mixture. Place back in oven and bake for 10-15 minutes until squash is fully cooked throughout. Serve immediately.
Store leftover picadillo in a tightly covered container in the refrigerator for 3-4 days or freeze up to 3 months