Move your oven rack to the lowest position to allow plenty of room for your roasting pan and set the oven temperature to 350 °F.
Place chicken on a large sheet pan, remove giblets, and pat dry with paper towels.
Melt butter, mix with minced garlic, ½ tablespoon poultry seasoning, ½ tablespoon salt and 1 teaspoon pepper.
Place onion and aromatics in chicken's cavity. Sprinkle with remaining ½ tablespoon poultry seasoning, ½ tablespoon salt and 1 teaspoon pepper. Brush the entire exterior with the butter mixture.
Place the extra onion and additional aromatics (such as sliced carrots and apples) on the bottom of the roasting pan and place chicken on top (breast side up), taking care to tuck the chicken wings so that they don't dry out.
If your oven has a "Convection Bake or Roast" setting, turn it to 325 °F Convection (If not, just roast it on regular at 350 °F). Cook for 1.25-1.5 hours until the internal temperature of the thickest part of the chicken taken with an instant-read thermometer is 165 F and the skin is golden brown.
Let chicken rest for 15 minutes (don't skip!).
Carve.
Serve.
Notes
LeftoversStore leftover oven-roasted chicken in an airtight container in the refrigerator for up to 4 days or freeze for up to 3 months. Thaw overnight in the refrigerator before reheating.Rewarm in the oven at 350 F or in the microwave.