Make the Apple Filling: In a pan over medium heat, melt the butter and add diced apples, sugar, and cinnamon. Cook for 3-4 minutes until softened. Mix cornstarch with water and stir into the apples. Cook until thickened, then remove from heat.
Prepare the Dough: Preheat the oven to 350°F (175°C) and grease a baking dish. Flatten each biscuit dough round and place a spoonful of apple filling in the center. Seal the edges to form a ball.
Coat and Bake: Dip each dough ball in melted butter, then roll in the cinnamon-sugar mixture. Place in the baking dish and bake for 18-20 minutes until golden brown.
Serve and Enjoy: Let cool slightly before serving. Enjoy warm for the best flavor!