Step 1

Adjust oven rack to lower-middle position and heat oven to 275 degrees. Using fork, poke thickest half of each breast 5 to 6 times; evenly sprinkle each breast with ½ teaspoon kosher salt (or ¼ teaspoon table salt). Place chicken, skinned side down, in 13 by 9-inch baking dish and cover tightly with foil. Bake until thickest part of breast registers 145 to 150 degrees on instant-read thermometer, 30 to 40 minutes.

Step 2

Remove chicken from oven and transfer, skinned side up, to paper towel-lined plate and pat dry with paper towels. Heat oil in 12-inch skillet over medium-high heat until smoking. While pan is heating, whisk butter, flour, cornstarch, and pepper together in small bowl. Lightly brush top side of chicken with half of butter mixture. Place chicken in skillet, coated side down, and cook until browned, 3 to 4 minutes. While chicken browns, brush with remaining butter mixture. Using tongs, flip chicken, reduce heat to medium, and cook until second side is browned and thickest part of breast registers 160 to 165 degrees on instant-read thermometer, 3 to 4 minutes. Transfer chicken to large plate and let rest while preparing pan sauce (if not making pan sauce, let chicken rest 5 minutes before serving).