Chocolate Caramel Slice

Chocolate Caramel Slice
(from Bon Appetit)
makes 16-20

crust:
1 cup all purpose flour
1/4 cup brown sugar
2 tsp cornstarch
1/4 tsp salt
1 stick unsalted butter, cut into pieces
1 tbs ice water
1 egg yolk

toppings:
14 oz can sweetened condensed milk
1/2 cup brown sugar
6 tbs unsalted butter, diced
2 tbs dark corn syrup
1 tsp vanilla extract
6 oz bittersweet or semisweet chocolate, coarsely chopped
2 tbs Maldon sea salt

preheat oven to 350 degrees F. grease a 8 1/2-inch square metal baking pan. blend flour, brown sugar, cornstarch and salt in a food processor. add butter and pulse until a coarse meal forms. add ice water and egg yolk and blend just until moist clumps form. press dough onto bottom of prepared pan evenly. pierce all over with a fork. bake 20 minutes or until golden brown. cool completely.
whisk together condensed milk, brown sugar, butter, corn syrup and vanilla in a medium saucepan over medium heat until sugar dissolves, butter melts and mixture comes to a boil. insert a candy thermometer and boil gently until caramel is thick and temperature reaches 225 degrees F. whisk constantly to prevent from burning. pour caramel evenly over cooled crust and let set 15 minutes. melt chocolate in a double boiler or in the microwave at 15 second intervals, stirring occasionally. spread melted chocolate evenly over caramel layer. sprinkle with sea salt and refrigerate until set, at least one hour. can be made three days ahead if covered and refrigerated. cut into bars and enjoy!