Preheat oven to 350 degrees.
Mix 1/3 cup evaporated milk, cake mix, and butter together. Dough will be stiff. Press half of the mixture in the bottom of a foil lined or greased 9 x 9 baking pan. Bake for 8-10 minutes. (Reserve the other half of the mixture for the top layer.)
While cake is baking, add caramels and milk to a microwavable mixing bowl. Microwave for 30 seconds, at half power. Continue to microwave in 30 second increments until caramels are melted and smooth. Add apples to caramel mixture. Stir.
Pour over first baked layer. Sprinkle with white chocolate chips.
Mold remaining blondie dough into a thin sheet and set over caramel layer. It’s okay if it doesn’t completely cover the caramel, or if it doesn’t look pretty. Everything will even out while it’s baking and life will be good again! Sprinkle walnuts over this layer if desired.
Bake for 20-25 minutes. Let cool a little and sprinkle with powdered sugar if desired.
Serve warm with vanilla ice cream and additional caramel if desired!