1. Prepare the Filling: Preheat the oven to 350°F (175°C). In a large pan, heat 2 tablespoons olive oil. Sauté onions until softened, then add ground beef and cook until browned. Remove excess fat and stir in spices. Optionally, add vegetables like leeks, mushrooms, or carrots for extra flavor.
2. Assemble the Pie: Lightly grease a baking pan (~10×6 inches or similar). Cut the phyllo sheets to fit the pan. Layer 3 to 4 sheets of phyllo, brushing each generously with olive oil or butter mixture. Spread the cooled meat filling evenly on the phyllo base. Continue layering phyllo sheets over the filling, ensuring each top sheet is well-brushed.
3. Cut and Bake: Carefully cut the assembled pie into squares with a sharp knife. Pour the milk and egg mixture over the entire dish. Bake on the middle rack for 30 to 45 minutes, or until golden brown and crispy. Optionally, broil briefly for extra crispness, watching carefully to avoid burning.
4. Serving and Storing: Serve warm, with a side salad or any preferred side dish. Refrigerate leftovers in an airtight container for up to three days, or freeze for extended storage. Reheat in the oven to maintain crispiness.