Add the stock to a pan and warm gently.
Fry the shallot in the butter for 3–4 minutes until starting to soften.
After 2 minutes add the garlic and stir together.
Add the rice and stir to coat in the butter for a minute.
Pour in the white wine and simmer until nearly absorbed.
A ladle or two at a time, add the warm stock and stir until nearly absorbed.
Continue until all the stock has been absorbed and the mixture is creamy.
Stir in the mascarpone until rich and creamy.
Add the lemon zest, lemon juice (you might not need it all), parsley and Parmesan (if using), and a good grind of black pepper.
Add the torn smoked salmon and combine well to warm through.
Serve topped with the remaining smoked salmon and a sprinkling of parsley.