Step 1Preheat oven to 180°C. Line a baking tray with baking paper. Boil 1 litre of water in the kettle.
Step 2Place parsnips and potatoes in a microwave safe bowl with ½ cup of water. Cover; cook on High for 12 minutes, or until tender. Drain.
Step 3Meanwhile, heat 1 tablespoon of olive oil in a large saucepan over medium-high heat. Sauté onion for 3 minutes, or until soft. Add stock cubes, milk, mustard and 1 litre of boiling water. Bring mixture to the boil, then reduce heat to medium-low and simmer, uncovered, for 5 minutes.
Step 4Meanwhile, place 4 heaped tablespoons of finely grated parmesan, about 5cm apart, on prepared tray. Flatten slightly. Bake for 5 minutes, or until the cheese turns golden. Set aside to slightly cool on tray.
Step 4Add parsnip and potato to milk mixture. Blend soup with a stick blender, until smooth. Return to the boil, if needed. Divide soup among serving bowls, garnish with chopped chives and serve with parmesan crisps and toast.