Preheat the oven to 275 F
Add the olive oil in a large pot. In medium to high heat, add the panchetta. Cook for 3-5 min until it is crispy outside but still soft inside. Transfer panchetta to a plate with a slotted spoon.
Pat chicken pieces dry with paper towel and season with salt and pepper.
Add the chicken pieces in batches of two to the leftover pancetta grease (skin side down for chicken thighs). Sear for about 5 minutes each side, until skin is rendered, crispy and browned. Transfer chicken to the plate with the panhetta. Set aside.
Add the diced onions and a pinch of salt to the pan and cook over medium heat for 5 minutes, while stirring occasionally, until the onions are transparent and lightly browned. Add the garlic and cook until fragrant (about 1 minute).
Add the tomato paste. Add the bay leaf, cloves, a large pinch of oregano and some freshly fround pepper. Stir well and saute for 2-3 min to bring out the flavors.
Add the chicken pieces and the pancetta back in the pot. Add the wine and the tomatoes. Stir gently and break the tomatoes a little. Add the thyme 5 sprigs thyme. Cover pot and transfer it into the preheated oven to cook for 2 hours.
Please check stew every 30 min or so in case you need to add any liquid.
Remove casserole from oven and place on stove. Mash the remaining butter with the flour and stir into the casserole (the heat will cook any lumps out). Bring the casserole to a simmer and cook for a further 10 minutes, until sauce has thickened.
Season to taste, if desired. Garnish with parsley and any extra thyme leaves, and serve immediately over mashed potatoes.