Preheat the oven to 200C/400F/Gas 6.
For the risotto, place the fish stock into a pan and bring to a gentle simmer.
Meanwhile, melt half of the butter in a heavy-bottomed pan over a medium heat, then add the shallot, garlic and leek and cook for a few minutes until softened but not coloured.
Add the rice and cook for a minute, stirring well to coat the rice in the butter.
Add the wine, bring to the boil and cook until the liquid is reduced by half.
Gradually add the warm fish stock, one ladleful at a time, stirring until the liquid is completely absorbed by the rice, before adding the next ladleful. Repeat this process until nearly all of the stock is absorbed and the rice is cooked but still al dente.
Add the flaked cooked haddock and stir to combine.
Add the remaining butter, the mascarpone, parmesan and parsley and season well with salt and freshly ground black pepper.
For the roasted haddock, melt the butter in a large ovenproof frying pan over a medium heat. Add the haddock fillets and fry for one minute on each side, then transfer to the oven to roast for 6-8 minutes, or until completely cooked through.
For the parsley oil, place the parsley and olive oil into a food processor and blend until smooth. Place a sieve over a bowl and pour the parsley oil into the sieve. Press through the sieve to collect the bright green parsley oil.
To serve, place a spoonful of risotto into the centre of each plate and top with a piece of the roasted haddock. Spoon the parsley oil around the plate and serve.