Start by preheating your oil in a deep skillet on medium heat, get it nice and hot for that crispy crust you want.
Season the chicken breasts with kosher salt, black pepper, and garlic powder evenly so every bite's packed with flavor.
Set up your breading station in three bowls: flour and cornstarch mix in one, the buttermilk combined with hot sauce (and egg) in another, and panko breadcrumbs in the last one.
Dredge each piece of chicken first in the flour-cornstarch mix, shaking off the extra dust, then dip in the wet buttermilk batter, and finally coat it thoroughly in the panko crumbs.
Carefully drop the coated chicken breasts into the hot oil and fry for 5 to 7 minutes each side till they turn that perfect golden crisp and are cooked through.
Remove each piece and drain on paper towels, then top 'em right away with mozzarella slices and let the cheese melt just a bit; it only takes a minute or two.
Now, place your chicken pieces in the pressure cooker along with a little broth or water to build pressure, seal up the lid, and start the cooking.
Watch for steam cues and wait for the pressure build until you set your timer. After cooking, do a natural release to let flavors settle before quick releasing any extra pressure to open up.
Notes
Serve sliders with bang bang sauce for added zing.