Initiate the preheating process of the oven to 325 degrees Fahrenheit.

Commence the preparation of the chicken breasts by cutting them into uniformly sized pieces. Subsequently, season the pieces with the designated amounts of salt and pepper.

Arrange two bowls. In the first, place the cornstarch, and in the second, deposit the beaten eggs. Systematically, immerse each chicken piece first into the cornstarch ensuring full coverage and then into the egg mixture, ensuring a complete coating.

Heat the canola oil in a skillet, setting the burner to medium-high heat. Once the oil reaches the desired temperature, introduce the chicken pieces, ensuring each side achieves a golden brown hue. Once completed, transfer the chicken pieces to a pre-greased 9 x 13 baking dish.

In a separate, medium-sized mixing bowl, amalgamate the granulated sugar, ketchup, apple cider vinegar, white vinegar, soy sauce, and garlic salt to produce the sauce. Once blended, dispense the sauce uniformly over the chicken pieces in the baking dish.

Position the baking dish in the preheated oven and allow the chicken to bake for 1 hour. Throughout the baking process, every 15 minutes, gently stir the chicken pieces to ensure that the sauce is consistently distributed.