Sprinkle chicken with ¼ teaspoon pepper and ⅛ teaspoon salt. Heat oil in a large skillet over medium heat until shimmering. Add the chicken; cook, turning once, until browned and an instant-read thermometer inserted into the thickest part registers 165°F, 6 to 8 minutes. Transfer the chicken to a plate.
Add shallot and garlic to the pan; cook, stirring until fragrant, about 15 seconds. Add broth; cook, stirring occasionally and scraping up the brown bits on the bottom of the pan, until reduced by half, 1 to 2 minutes. Stir in cream, lemon juice, lemon slices and the remaining ¼ teaspoon pepper and ⅛ teaspoon salt; simmer until slightly thickened, 1 to 2 minutes. Add the chicken, with any accumulated juices, and dill; turn to coat with the sauce. Sprinkle with additional dill, if desired.
