Preheat the convection/fan oven to 190 °C. Slice the 450 g chicken breasts in half to make 4 pieces. Season both sides with a total of ½ teaspoon salt and ¼ teaspoon ground black pepper.
Place 65 g all-purpose flour in a shallow dish. Beat 1 large egg in a second dish, then place 125 g French fried onions in a third dish, leaving them whole.
Dredge each chicken piece in the flour, shake off the excess, then dip it into the beaten egg. Coat both sides with the French fried onions, pressing gently to help them adhere.
Arrange the coated chicken on a mesh baking basket in a single layer. Bake for 15 minutes, checking that the center of each piece reaches 74 °C; continue cooking if needed.
Notes
Onion choice: Use crispy, ready-made French fried onions. Fresh onions will not produce the same coating.Light flour layer: Shake off loose flour so the egg can form an even coating without dry, floury patches.Handle gently: Lift the coated pieces carefully when transferring them to the baking basket to keep the whole onions attached.