1 cup butter
3/4 cup packed dark brown sugar
1 extra-large egg yolk
1-1/2 cups all-purpose flour
1/4 teaspoon salt
1 14-ounce can sweetened condensed milk
2 tablespoons unsalted butter
2 teaspoons vanilla
1 12-ounce package semisweet chocolate chips
1 cup almond brickle pieces
2 tablespoons cocoa nibs
Preheat oven to 375°F.
Line a 10" x 10" pan* with foil leaving a 2" tail on either end. Spray the foil and all sides of the pan with Pam. Using the foil will allow you to lift the cookies in one slab from the pan allowing for easy and attractive cutting. If you don't want to do this, just spraying the pan on bottom and sides with Pam will work just fine.
Cream together 1 cup butter and brown sugar with an electric mixer. Add egg yolk; beat well. Stir in flour and salt, mixing just to combine. Spread dough into prepared pan and bake 22-25 minutes, or until light brown. Remove from oven to wire rack. Reduce oven heat to 350°F.
Combine condensed milk and 2 tablespoons butter in a microwave-safe bowl and microwave, in 1-minute intervals, until thick and bubbly, stirring after each minute for a total of 4 minutes. Stir in vanilla. Spread mixture evenly over baked cookie layer. Return pan to oven and bake about 12 minutes, or until top is golden.
Sprinkle warm baked layers with chocolate chips. Return to oven for 1-2 minutes, or until the chocolate is glossy and melted. Spread chocolate evenly over baked layers. Top with an even layer of brickle chips and cocoa nibs. Allow to cool for 30 minutes, then place in the fridge to set chocolate for 30 more minutes. Cut into squares and store, covered, in the fridge.
* You can also use a 9" x 9" pan and bake for a minute or two longer, or a 9" x 13" pan (that was called for in the original recipe), but I find this makes the crust layer way too thin.