Step 1 Preheat oven to 200ºC. Place potato into a large saucepan, cover with cold water then bring to the boil. Boil, uncovered, for 15 minutes or until tender. Drain. Mash potatoes in a bowl.
Step 2 Stir in milk, table spread and green onion. Cover to keep warm.
Step 3 Meanwhile, heat oil in a large saucepan over high heat. Cook onion, thyme and leeks, stirring, for 5 minutes or until softened. Add mushrooms. Cook, stirring, for 7 minutes or until tender.
Step 4 Stir in paprika and Worcestershire sauce. Cook, stirring, for 1 minute or until fragrant. Add crème fraîche and stir until smooth and combined. Remove from heat.
Step 5 Transfer to 4 x 1 1/4 cup-capacity individual ramekins or a 6 cup-capacity baking dish. Top with mashed potato. Spray with a little oil. Bake for 30 minutes, or until top is light golden and warmed through.