Preheat oven to 325℉.
Pat chicken breasts dry and season with kosher salt and black pepper.
Preheat cast iron skillet on medium high heat.
Add avocado oil to skillet and sear chicken on both sides, 2 minutes per side.
Add chicken stock, lemon juice, and butter to skillet and place in oven for 15 minutes or until internal temperature of thickest part of chicken breast reads 165℉.
Remove chicken from pan and place on cutting board to rest.
While chicken is resting place skillet back on the burner on medium heat and reduce cooking liquid by half. Drizzle over chicken and enjoy!