Twixy Shortbread Bars

Step 1: In a large bowl, beat 1-1/2 cups butter with an electric mixer on medium to high speed for 30 seconds.

Step 2: Add sugar and 1-1/2 teaspoons vanilla; beat until combined, scraping sides of bowl occasionally.

Step 3: Beat in as much of the flour as you can with the mixer; stir in any remaining flour.

Step 4: Cover and chill for 30 to 60 minutes or until dough is easy to handle.

Step 5: Preheat oven to 350 degrees F.

Step 6: Line a 13x9x2-inch baking pan with foil, extending foil over edges of pan.

Step 7: Press dough evenly into bottom of prepared baking pan.

Step 8: Bake for 20 to 25 minutes or until top is lightly browned.

Step 9: Cool in pan on a wire rack.

Step 10: Spread dulce de leche in an even layer atop cooled crust.

Step 11: In a medium saucepan, heat whipping cream, 6 tablespoons butter, and the corn syrup to boiling over medium heat, stirring to dissolve syrup.

Step 12: Remove from heat.

Step 13: Add chocolate and vanilla to saucepan. Do not stir. Let stand 5 minutes.

Step 14: Stir until smooth. Let stand 10 minutes at room temperature to cool slightly.

Step 15: Slowly pour chocolate mixture over dulce de leche layer, spreading evenly.

Step 16: Cover and chill 1 to 2 hours or until chocolate layer is set.

Step 17: Layer bars between sheets of parchment or waxed paper in an airtight container; cover.

Step 18: Use the foil to lift uncut bars out of pan. Cut into bars.

Step 19: Store in the refrigerator for up to 3 days or in the freezer for up to 3 months.