Place 1/3 cup cornstarch in shallow dish or pie plate. In second shallow dish, whisk buttermilk,mustard, and garlic until combined.
Process cornflakes, 1/2 teaspoons salt, 1/2 teaspoons black pepper,and remaining 1/3 cup of cornstarch in food processor until conrflakes are finely ground, about 10 seconds. Transfer cornflake mixture to third shallow dish.
Adjust oven rack to middle position and heat oven to 200 degrees.
With sharp knife, cut 1/16" deep slits on both sides of chops, spaced 1/2" apart, in crosshatch pattern. Season chops liberally with salt and pepper. Dredge 1 chop in cornstarch; shake off excess. Using tongs, coat with buttermilk mixture; let excess drip off. Coat with cornflake mixture; gently pat off excess. Transfer coated chop to wire rack set in rimmed baking sheet and repeat with remaining chops. Let coated chops stand for 10 minutes.
Heat 1/3 cup oil in 12" nonstick skillet over medium-high heat until shimmering. Place 4 chops in skillet and cook until golden brown and crispy, 2-5 minutes. Carefully flip chops and continue to cook until second side is golden brown, crispy, and center of chop registers 140 degrees on instant read thermometer. Transfer chops to paper-towel lined plate and let drain for 30 seconds.Transfer to clean wire rack set over rimmed baking sheet, then transfer to oven to keep warm. Discard oil from skillet and wipe clean with paper towels. Repeat process with remaining oil and pork chops.