Bring the pasta pot to the boil with well-salted water. Poach the fresh spinach in the pasta water for 2 minutes and then rinse in very cold water. Squeeze the spinach well and set aside.
Bring the chicken stock to the boil in a pan and stir in the mascarpone. Let the liquid cool down a bit and stir in the egg yolk. Halve the garlic clove, roughly chop the spinach and add both to the sauce together with freshly ground coriander and a little olive oil. Bring to the boil and add a little truffle oil just before serving.
Cook the pasta in well-salted water according to the package instructions.
To serve, grate the Parmesan fresh over the dish and pluck some basil over the top.