Preheat your oven to 375°F and spray a 10x15-inch jelly roll pan with non-stick cooking spray.

Whisk together the flour, sugar, baking soda, cinnamon, and salt in a large bowl.

Heat the butter and water in a medium saucepan over medium-high heat until the butter melts and the mixture begins to simmer.

Remove from heat and pour it into the dry ingredients. Stir until just combined.

Mix in the eggs, sour cream, and vanilla extract until smooth.

Pour the batter into the prepared pan and spread evenly.

Bake for 18-22 minutes, or until a toothpick inserted in the center comes out clean. Cool in the pan for 5-10 minutes.

Melt the butter and milk together in a medium saucepan over medium heat, then bring it to a simmer over medium-high heat.

Combine powdered sugar, vanilla, and cinnamon in a large bowl. Gradually whisk in the hot butter mixture until smooth.

Pour the frosting over the warm cake, spreading it evenly with a spatula.

Allow the cake to cool completely.

Melt 2 tablespoons of butter in a large pot over medium heat. Add the diced apples and cook for 5 minutes, stirring often.

Mix the brown sugar, corn starch, and cinnamon in a small bowl, then stir it into the apples.

Cook over medium heat, stirring occasionally, until the apples are tender but not mushy (you don’t want applesauce!). Allow to cool completely.

Spread the cooled apple topping over the frosting, then drizzle with caramel sauce (optional but encouraged for a sweet finishing touch!).