Combine cornstarch and chicken broth in a small bowl. Set aside.
Combine flour, salt and pepper in a separate, shallow dish.
Cut chicken breasts in half, width-wise. Place each one between two pieces of plastic wrap, and pound them to ½" uniform thickness. Dry them with a paper towel, and then dredge them through the flour mixture, until their surface is coated on both sides.
Heat oil a large skillet over medium heat. Add chicken; cook 4 minutes per side, only turning once. Check for done-ness with an instant-read meat thermometer; it should reach 165º. Remove from heat, set aside, and top with foil to keep warm.
Brown the lemon slices in the skillet, 30-60 seconds. Remove from skillet.
Melt butter in skillet, still on medium heat. Add garlic, and stir for 30 seconds. Do not let the garlic burn! Pour in the wine, and stir, to de-glaze the pan. (The action of scraping the fond off the bottom of the skillet with a wooden spoon. All those bits = flavor!)
Whisk the cornstarch/broth mixture again, and pour into the skillet. Bring to boiling, and then turn heat to low. Simmer for a minute or two, until sauce has thickened to a gravy-like consistency.
Stir in lemon juice, papers, and thyme.
Drizzle chicken with sauce, top with lemon slices and more fresh thyme.