Pat the chicken breasts dry with paper towels and season generously with salt and pepper.
Heat the olive oil in a large skillet over medium-high heat.
Add the chicken and sear for 6–7 minutes per side until golden brown. Work in batches if needed.
Transfer the chicken to a plate.
Reduce the heat to medium and melt the butter.
Add the chopped shallot, garlic, salt, and pepper. Cook for about 1 minute until fragrant.
Stir in the flour and cook for another minute while stirring constantly.
Gradually whisk in the half-and-half and chicken broth until smooth.
Bring the sauce to a gentle boil, then reduce to a simmer.
Return the Creamy Lemon Garlic Skillet Chicken to the pan and simmer for 3–4 minutes until fully cooked and the sauce thickens.
Stir in the fresh lemon juice.
Garnish with parsley and lemon slices before serving.