Preheat the oven to 400°F. Add your breadcrumbs onto 2 rimmed baking sheets and spread out evenly. If you only have one baking sheet, then use half of the panko breadcrumbs and repeat when done. Spray the breadcrumbs with the cooking spray, and bake for ~2-3 minutes. Give the pan a good shake or mix the breadcrumbs around with a spatula, and bake for an additional 2-3 minutes. The breadcrumbs should be nice and golden brown, not burnt.
Once all your breadcrumbs are toasted, add them to a medium sized bowl. Add the salt, black pepper, onion powder, paprika, garlic powder, and cayenne (if using) and whisk together until completely mixed. I really enjoyed this spice blend, but this is a great place to experiment with other spices as you'd like, like dried basil and thyme, or even ground parmesan!
Slice the chicken breast into ~1" cubes. It doesn't need to be exact, but try to keep the sizes as close as possible or else some of the nuggets will finish cooking well before others. Once the chicken is all cut, in a small bowl, whisk together the eggs and milk until completely combined. Line a baking sheet with parchment paper or tin foil, and then place a wire rack on top. Spray the wire rack down with more cooking spray.
With each piece of chicken, use one hand to dunk it in the egg/milk mix, and then drop it into the breadcrumb bowl. Then use your other hand to toss breadcrumbs around on top of it, fully covering the nugget. Alternatively, you can use a small pair of tongs in your off hand to help coat the nugget, and then transfer it to the wire rack. Repeat with the rest of the chicken, leaving a little space between each nugget. Depending on the size of your pieces, you may need to either bake the nuggets in batches or use two baking sheets with wire racks.
When all the chicken is coated and ready to bake, give the nuggets a light spray of cooking spray, and bake for 15-20 minutes. I recommend using a cooking thermometer to test the internal temp of the chicken to gauge doneness. Test the largest nugget, and the chicken will be done when the internal temp reads 165°F.
When the chicken is done, remove from the oven and allow to cool for a few minutes before serving.
Enjoy!
