Pat the chicken pieces dry and season both sides with sea salt and freshly ground black pepper.
Heat 2 tablespoons extra virgin olive oil in a large skillet over medium heat until shimmering.
Add the chicken to the skillet and cook until browned on the first side, about 5–7 minutes.
Turn the chicken pieces, place the thin lemon slices on top, and continue cooking until the second side is browned and the chicken is cooked through (internal temperature 165°F), about 8–12 more minutes depending on piece size.
Remove the chicken and lemon slices from the pan and set them aside on a plate while you make the sauce.
In the same skillet over medium heat, add the minced garlic and 1 tablespoon flour; cook and stir until the mixture becomes bubbly and fragrant, about 30–60 seconds.
Slowly whisk in 3/4 cup milk, then add 1 tablespoon lemon juice, 1 tablespoon chopped parsley, and 2 teaspoons fresh thyme; bring the mixture to a gentle boil while whisking.
Reduce heat to low and simmer the sauce for about 5 minutes, stirring occasionally, until it thickens to your liking.
Return the browned chicken to the skillet and spoon the lemon-garlic sauce over the pieces before serving.
