Preheat skillet over medium heat. Preheat oven to 425 degrees. Cut a slit in each chicken breast. Stuff each with 2 tablespoons of cream cheese. Set aside. Mix together the sesame seeds, poppy seeds, garlic, onion and kosher salt.
Set up breading station. Fill one pie plate with flour and season lightly with salt and pepper. In another pie plate, crack the egg and whisk it with a splash of milk. In the last pie plate, mix together the panko and all but 1 tablespoon of the spice mix. Dredge the chicken in the flour, then the egg and last in the breadcrumb mixture.
Heat olive oil in the skillet and cook chicken for 4 minutes per side. Place skillet in the preheated oven and bake for 15 minutes, or until no longerpink and cooked through.
Meanwhile, toss the potatoes with the olive oil and remaining 1 tablespoon spice mixture. Place in a single layer on a baking sheet. Cook for 40 minutes, flipping halfway through.