Pat chicken breasts dry and season with salt and pepper. Do not season chicken with the lemon pepper seasoning, it will burn when browning.
Heat olive oil to medium high and cook chicken breast 5-7 minutes on each side until breasts reach an internal temperature of 165℉. Depending on size of pan and chicken breast, you may need to cook the chicken in two batches. When chicken is ready, set aside to rest while creating the sauce.
Reduce heat to medium-low and add butter to pan, sauté shallots for 1-2 minutes then add garlic and cook for another minute. Sprinkle in flour stirring constantly and toast for about 2 minutes. Add chicken broth and increase heat to medium heat scraping up brown bits. Add half and half and whisk until smooth. Bring sauce to a boil and reduce to a simmer until slightly thickened. Stir in fresh lemon juice and lemon pepper seasoning. Taste and adjust sauce as needed. Add chicken breasts and lemon slices to sauce and let heat through. Sprinkle with fresh parsley and additional lemon pepper seasoning as needed.