Toffee Millionaires Variations

This comes from Doug and Chris. It's a Martha Stewart recipe, but it's still really good!

Makes 16 squares

2 cups flour
1 ¼ teaspoons coarse salt
1 cup unsalted butter softened plus more for the pan
¾ cup light-brown sugar

Preheat oven to 300 with rack in upper third. Sift flour and salt into a bowl, set aside

Put butter into the bowl of an electric mixer fitted with the paddle attachment. Mix on medium-high speed until fluffy, 3 to 5 minutes, scraping down sides of bowl. Gradually add sugar, beat until pale and fluffy (about 2 mins)

Reduce speed to low. Add flour mixture all at once, mix until just combined.

Using plastic wrap, press dough evenly into a 8-inch round springform or cake pan pan. With plastic on dough, refrigerate 45 minutes. Prick all over with a wooden skewer. Bake until golden brown and center is firm, 70 – 75 minutes. Transfer to a wire rack; let cool 10 minutes. Put 1 cup finely chopped chocolate-covered toffee bars and ¼ cup heavy cream into a saucepan. Cook, stirring constantly, over medium-low heat until smooth. Pour over shortbread in pan; sprinkle with about 1/3 cup coarsely crushed chocolate-covered toffee bar. Let cool completely. Cut into 2-inch squares. Store airtight up to 1 week.