Cook uncovered 15 min. Check for browning of the drippings and add small amount of water if needed to bottom of pan. After 30 minutes, add onion slices and garlic clove slices to top of chicken and around the bottom of the pan.
Continue cooking uncovered until thermometer inserted in innermost part of thigh and wing and the thickest part of the breast reads at least 165℉. I use this formula to help with estimated total cooking time: 15 min per pound then round up to nearest 5 min. Check chicken every 15-20 min to see if water needs to be added to the bottom of the pan. You want drippings to brown, but not burn.
Let cool 15-20 min, then carve. (Save bones and remnants for bone broth!)
While chicken is cooking make Walnut Gravy:
Add all ingredients except pan drippings to blender and blend until smooth. Pour into small saucepan.
Before serving add 2-3 Tablespoons pan drippings and heat over medium low. Adjust drippings amount to desired gravy thickness.