Season the chicken with salt and pepper and let it sit in the fridge, uncovered, overnight.
Preheat the oven to 475°F degrees.
Place the onions, garlic, potatoes and pancetta in the bottom of a 5.5 quart Dutch oven (pancetta on top).
Gently separate the skin on the breast and legs from the meat and stuff with the 4 pats of butter.
Stuff the cavity of the chicken with the halved lemon, fresh thyme and fresh sage. Place in the Dutch oven.
Rub the bacon fat on the skin and pour the white wine over the chicken.
Roast, uncovered, for 15 minutes, until the skin has started browning.
Reduce the heat to 350°F degrees and roast for an additional 2 hours, basting 1-2 times throughout.
The chicken should register 160°F degrees at the thickest part of the thigh when you remove it from the oven.
Let it rest for 10 minutes, carve, then serve. **Optional: squeeze the lemon from the cavity over top of the chicken.
While the chicken rests on a cutting board, place the Dutch oven with the potato mixture back in the oven at 500°F degrees and cook until the potatoes caramelize, about 5-10 minutes.
Notes
Leaving the chicken uncovered while it sits in the fridge allows the skin to dry, which helps ensure perfectly crispy and golden skin when roasting.
Make sure the chicken you buy will fit in your Dutch oven.
Chicken is safe to eat at 165°F degrees. Cook the chicken to 160°F degrees and remove from the heat. The temperature will continue to rise to 165°F degrees as you let it rest for 10 minutes. Use an instant read thermometer to check the temperature.
Typically time is 15-20 minutes per pound, so adjust the cook time to your chicken size. Using a thermometer will help you determine when it's done.
You can tie the legs with kitchen twine if you'd like, but it's not necessary.
If the skin of the chicken starts to brown too much, cover it loosely in aluminum foil while it finishes roasting.
Depending on the size of your chicken, you may need to adjust the roasting time slightly.