Preheat oven to 350°F. Line a 9-inch square baking dish with parchment paper.

In a small bowl, mix diced apples with a tablespoon of flour and cinnamon. Set aside.

In a large bowl, combine melted butter and brown sugar until smooth. Add egg and vanilla, mix well.

Add flour and salt to the wet ingredients and stir until just combined. Fold in diced apples and toffee bits.

Pour batter into prepared baking dish and spread evenly. Bake for 25 minutes or until a toothpick inserted in the center comes out clean.

Remove from oven and let cool completely before frosting.

For the frosting, beat softened butter until fluffy. Add powdered sugar gradually, then mix in caramel sauce and heavy cream until smooth.

Spread frosting over cooled blondies. Decorate with additional toffee bits if desired. Slice into squares and serve.