Instructions
1 Set a large non-stick frying pan over medium heat. Heat olive oil. Add onion, garlic, carrot, celery and mushrooms; cook, stirring often, for 5 minutes, or until soft. Increase heat to medium high.
2 Add beef mince to frying pan and stir with a wooden spoon (to break up) for 4-5 minutes, or until browned. Scatter mince with flour and cook, stirring, for 1 minute. Stir passata, tomatoes and Worcestershire sauce into mince and bring to the boil. Reduce heat to medium-low. Cover pan partially and simmer, stirring occasionally, for 15 minutes. Stir in frozen peas.
3 Meanwhile, boil potatoes in a large saucepan of boiling water for 10-12 minutes, or until tender. Drain potatoes and return to pan. Reduce heat to low. Toss potatoes until dry, then remove from heat, add milk and mash until smooth.
4 Preheat oven to 200°C. Line a large baking tray with a sheet of baking paper. Spray 4 x 2-cup ovenproof, microwave-safe dishes with oil. Spoon mince mixture into dishes and top with mashed potato. Put dishes on prepared tray and bake for 15-20 minutes, or until edges bubble and potato is just golden. Leave pies to cool slightly. Cover dishes with plastic wrap and freeze (for up to 3 months).