Line an 8”x8” brownie pan with parchment paper or aluminum foil. (Tip: Make the parchment or foil sheets extra long so that they extend over edges of the pan. This will make it easy to lift the brownies out later!)

Using an electric mixer, cream together the butter and granulated sugar until light and fluffy (2-3 minutes on medium speed).

Add the powdered sugar, vanilla and flour. Mix on low speed until a stiff dough forms. Cover dough and refrigerate for 1 hour.

Preheat oven to 325°F.

Press dough evenly into bottom of prepared pan. (Note: A flat-bottomed glass helps quite a bit here.)

Bake for 35-40 minutes, or until tops of cookies turn light brown.

Set pan aside to cool.

Place the unwrapped caramels, evaporated milk and 1 tablespoon of water in a large, microwave-safe bowl. Heat in microwave for 30 second intervals, stirring after each interval. (Note: It took me 5 rounds before mixture was fully melted and smooth.)

Spread caramel mixture evenly on top of the shortbread cookie layer, using an offset spatula to push caramel to the edges of the pan.

Using a small saucepan, add the semi-sweet chocolate, butter and heavy cream. Place over low heat and cook, stirring often, until chocolate and butter have melted and mixture is smooth.

Pour mixture on top of the caramel layer, using an offset spatula to push chocolate to the edges of the pan.

Cover pan and refrigerate for at least 3 hours.

Lift the bars out of the pan and cut into 1”x1” squares.