1. Preheat oven to 180°C/160°C fan forced. Grease 4 x 1 cup (250mL) capacity individual overproof serving bowls.
2. Cook potatoes in boiling water for 8 minutes or until just cooked; drain.
3. Meanwhile, heat oil in a medium frying pan; add onion, cook 2 minutes. Add beef, cook until golden brown, breaking any lumps formed. Add mushrooms and MAGGI Lamb Casserole Recipe Base, cook 1 minute. Add vegetables and water, bring to boil, simmer 3 minutes, stirring occasionally.
4. Divide mixture between prepared serving bowls. Top each with potato slices, sprinkle cheese evenly over top; bake for 20 minutes or until bubbly and golden.