How to skillet-poach chicken breasts:

Cup of Yum
1. Dry the chicken with paper towels and sprinkle both sides with salt and pepper (I like 1/4 teaspoon each). Heat the oil in a large skillet over medium-high heat until shimmering.
2. Add the chicken in a single layer and cook until golden-brown on one side, 4 to 5 minutes. Flip the chicken over, add the water and aromatics (if using), and cover.
3. Reduce heat to medium and continue to cook until the chicken registers 165 degrees when pierced at the thickest part, about 10 to 15 minutes longer depending on the thickness of the chicken.
4. Remove to a cutting board and cool slightly. Slice, chop, or shred as desired.

How to poach a whole chicken:

1. Add chicken to a large Dutch oven or stockpot. Add aromatics and salt. Fill pot with cold water, until water covers the chicken by about an inch.
2. Bring water to barely a boil over medium-high heat. Skim off any white foam and discard. 
3. Reduce water to low, cover, and continue to simmer for 20 minutes. Chicken is done when opaque through the middle and a thermometer in the thickest part of the chicken registers 165 degrees.
4. Remove chicken from pot. Shred chicken, discarding skin and bones (you should have about 4 cups chicken). See notes for how to save the remaining chicken broth.