Preheat the oven to 220 °C.
Heat a frying pan, add olive oil and sear the guineafowl (skin sidedown first) for about 2 minutes on each side over a medium heat. Do not forget to grind salt and pepper on both sides.
Remove from the pan, place on a baking tray and finish cooking in the oven for 7-9 minutes. In the meantime, cook the polenta.
In a 3-quart pan over high heat, bring milk to a boil. Reduce heat to a low boil.
Stirring constantly, pour in polenta in a slow, thin stream, pausing occasionally to break up any lumps. Stir in ½ teaspoon salt.
Reduce heat and simmer, stirring often, until polenta is thick and creamy to bite and pulls away slightly from sides of pan when stirred, 20 to 40 minutes*. Adjust heat as necessary to maintain a simmer.
While polenta cooks, remove the guineafowl from the oven and allow to rest a little before serving.
Melt butter in a 10- to 12-inch frying pan over medium heat. Stir in mushrooms. Stir often until liquid has evaporated and mushrooms are browned, about 7 minutes.
Stir mushrooms, mascarpone cheese, parmesan cheese, truffle oil, and sherry vinegar into polenta. Season to taste with salt and pepper.
Place polenta on serving plates and dizzle with more truffle oil to taste. Add the guineafowl forequarters.
Enjoy your meal!