Coarsely chop the hazelnuts, walnuts and almond sticks in the speed chopper.
Bring the milk and vegetable stock to the boil in a saucepan, add a bay leaf. Slowly pour in the corn grits while stirring and bring to the boil over a medium heat, cover and let swell for 10 minutes, stirring occasionally.
Finely grate the Parmesan. Roast the nuts and almonds in a pan without fat until light brown. Stir half of the roasted nuts, almonds and Parmesan into the polenta (if it has become too firm, just add a little more vegetable stock). Season to taste with salt and pepper.
Clean the mushrooms and cut into thin slices. Heat the rapeseed oil in a pan and fry the mushrooms until light brown, season with salt and pepper. Pluck the parsley leaves from the stems and roughly chop. Stir the butter and parsley into the mushrooms.
Arrange the nut polenta with the mixed mushrooms on plates. Serve sprinkled with the remaining nuts and Parmesan.