Skinny Sweet and Sour Chicken

Disclaimer: Sweet and Sour chicken is never healthy, but this one isn't fried, so... it's a little skinnier, right?

1-2 pounds chicken breasts, cut into chunks
salt and pepper for seasoning
2 TB vegetable oil
1/2 cup sugar
3/4 cup apple cider vinegar
1/3 cup ketchup
1 1/2 TB soy sauce
3/4 tsp garlic powder
1 can pineapple chunks 

Preheat the oven to 325 degrees. Spray a 9x13 baking dish with cooking spray. Set aside.
Cut the chicken breasts into chunks and season with salt and pepper.
Heat vegetable oil on medium low in a large skillet. When the oil is warm, saute the chicken until cooked through. Drain chicken onto a paper towel to get the excess oil off.
In a small bowl, combine the sugar, apple cider vinegar, ketchup, soy suace and garlic powder. whisk until completely combined. Drain the pineapple chunks, saving the juice. Slowly add pineapple juice to taste into the sauce mixture (I think I use about 1/3 a cup of pineapple juice).
Place chicken in the baking dish and add the sauce. Toss to combine. Add pineapple chunks on top.
Place in the oven and bake until sauce is bubbling and thick, about 45-55 minutes. Toss chicken to completely coat every 15 minutes.
Serve immediately with rice.