Start by rinsing your chicken breast and patting it completely dry with paper towels. Cut it into small, even cubes, roughly the size of a large gummy bear, since uniform pieces cook at the same rate. If your toddler is very young, cut the pieces even smaller so they're easier to chew and manage.
Line up three shallow bowls: one with flour, one with the beaten egg mixed with water, and one with the breadcrumbs combined with garlic powder, onion powder, salt, and pepper. Keeping these separate and in order stops your fingers from turning into a breaded mess halfway through.
Take each chicken cube and dredge it first in the flour, tapping off the excess. Dip it into the egg wash next, letting any extra drip away. Finally, press it into the breadcrumb mixture so the coating sticks on all sides. Set the coated piece on your prepared baking sheet.
Once every piece is coated, spread them out on the baking sheet in a single layer with a little space between each nugget. Lightly spray or drizzle them with oil. This step is what gives you that golden, slightly crisp shell without needing to fry anything in oil.
Bake the nuggets at 400°F for about 12 to 15 minutes, flipping them halfway through so both sides get color. They're done when the coating turns golden brown and the internal temperature of the chicken reaches 165°F on a meat thermometer.
Let the nuggets rest on the tray for two to three minutes once they come out of the oven. This short rest keeps the coating crisp and lets the inside finish cooking gently. After that, they're ready to plate and serve while still warm.