Pre-heat an oven to 360°F (180°C). Prepare the filling by mixing together the mascarpone, the sage, the thyme, the rosemary, the lemon zest and seasoning generously with salt.
Gently peel back one side of the skin of the chicken thighs, so that it forms a pocket into which the stuffing can be filled. Place about 1 tbsp of the filling into this pocket.
On the flesh side of the chicken, spread a further 1 tsp of the filling and then place 1 slice of prosciutto on top. Roll the chicken up, with the skin on the outside, and place into a shallow sided baking tray.
Place the chicken into the oven for 20 minutes, or until the chicken in cooked through and the skin is nice and crisp.
In a bowl mix together the egg yokes and the lemon juice. Once cooked, remove the chicken from the baking tray. To the juices remaining in the pan, add the egg yolk and lemon juice mixture, and mix thoroughly to create a sauce, which should be drizzled over the chicken.
To prepare the green beans, add the olive oil to a frying pan over a medium high heat, and pan fry the green bean and garlic cloves, until the beans are tender. Remove the garlic cloves and serve the green beans alongside the chicken. Garnish the chicken with some chopped parsley, and enjoy!
If you prefer skinless chicken, simply put all of the mascarpone inside the thigh with the prosciutto and roll.