1
Combine the lemon, parsley, garlic, oil and salt in a blender until mostly smooth.
2
Toss the chicken with half of the gremolata and marinate overnight or for at least 4 hours. Reserve the remaining gremolata for mushrooms.
3
Preheat the oven to 450°F.
4
Remove the chicken from the marinade, discard marinade and season chicken with salt and pepper. Roast on a baking sheet until golden, about 15-20 minutes.
5
Reduce the oven to 350°F
6
In a large, cold braising dish, heat the oil, garlic, chile flakes and rosemary until the garlic starts to turn golden and crisp. Add the onions, peppers, tomato sauce, wine and chicken stock. Bring to a boil, reduce the heat to a simmer and cook for 15 minutes.
7
Place the chicken thighs into the braising dish with the sauce. Cover tightly and braise in the oven for 45 minutes, until the chicken is very tender. Remove from the oven and stir in the fresh basil.
8
Meanwhile, in a large pot, bring the water, milk, butter and salt to a boil. Reduce the heat to low and whisk in the polenta. Cook, stirring regularly, for 20 minutes. Fold the cheese into the polenta and cook for 10 more minutes. Season with salt and pepper.
9
Toss the oyster mushrooms with the reserved gremolata on a baking sheet. Roast for 12-15 minutes, or until golden brown.
10
To serve, divide the polenta between plates. Top with chicken cacciatore and serve with oyster mushrooms.