Heat the oven to 425°F. Spray a roasting pan with vegetable cooking spray.
Brush the pork with the oil and season with 1/2 teaspoon salt and black pepper. Place the pork in the pan. Stir the apples, squash, brown sugar, cinnamon, onion, 1/2 teaspoon salt and 1/2 cup stock in a large bowl. Add the apple mixture to the pan.
Roast for 25 minutes or until the pork is cooked through, stirring the apple mixture once during roasting. Remove the pork from the pan and keep it warm. Roast the apple mixture for 15 minutes or until it's browned. Remove the apple mixture from the pan.
Stir the remaining stock and flour in a small bowl until the mixture is smooth. Stir the stock mixture in the pan. Cook and stir over medium-high heat until the mixture boils and thickens, scraping up the browned bits from the bottom of the pan. Serve the stock mixture with the pork and apple mixture.