Step 1: Prepare the Apples

1. Preheat the Oven: Set your oven to 350°F (175°C).
2. Arrange Apples: Grease a 9×13-inch baking dish with butter or nonstick spray. Spread the peeled and chopped apples evenly across the bottom of the dish.

Step 2: Mix the Cake Layer

1. Combine Dry Ingredients: In a medium-sized mixing bowl, stir together the yellow cake mix, brown sugar, granulated sugar, and ground cinnamon until evenly blended.
2. Layer the Cake Mix: Sprinkle the dry cake mixture evenly over the apples in the dish.

Step 3: Add Butter and Water

1. Drizzle Butter: Slowly pour the melted butter over the top of the cake mix layer, ensuring it covers as much surface area as possible.
2. Add Water and Vanilla: Drizzle the water evenly over the top, followed by the vanilla extract. This helps moisten the dry ingredients and ensures an even bake.

Step 4: Bake the Cake

1. Bake: Place the baking dish in the preheated oven. Bake for 40-45 minutes, or until the top is golden brown and the apples are tender.
2. Check for Doneness: Insert a toothpick or knife into the center. If it comes out clean or with a few moist crumbs, the cake is ready.

Step 5: Make the Cinnamon Glaze

1. Mix Glaze Ingredients: In a small bowl, whisk together powdered sugar, milk, vanilla extract, and ground cinnamon until smooth.
2. Adjust Consistency: If the glaze is too thick, add more milk, one teaspoon at a time, until it reaches your desired consistency.

Step 6: Serve the Cake

1. Cool and Glaze: Allow the cake to cool slightly for 10-15 minutes before drizzling the cinnamon glaze over the top.
2. Serve: Slice into squares and serve warm. Pair with a scoop of vanilla ice cream or a dollop of whipped cream for extra indulgence.