1. Heat 1 tbsp of the oil and 2 tbsp of the butter in a large frying pan over medium-high heat. In two batches, add the pheasants and cook, turning occasionally, about 10 minutes, until browned. Season with salt and pepper. Transfer to a large casserole large enough to hold both birds snugly.

2. Add the mushrooms and thyme to the frying pan and cook about 5 minutes, until browned. Add to the casserole.

3. Preheat the oven to 375°F (190°C). Add the remaining 1 tbsp oil to the pan. Add the onion and bacon and cook, stirring often, for 5 minutes, or until the onion starts to brown. Add to the casserole. Add the wine and bring to a simmer over medium heat. Cover and bake for 1½ hours, or until a pheasant leg pulls away from the bird easily. Transfer the pheasants to a platter. Strain the solids, reserving the liquid, and add the solids to the platter. Tent with aluminum foil to keep warm.

4. Skim the fat from the cooking liquid. Return to the casserole and boil about 10 minutes, until reduced by two thirds. Remove from the heat, whisk in the remaining butter, and season. Transfer to a sauceboat. Carve the pheasant and serve with the sauce.