1 cup flour
1/2 cup (1 stick) cold Challenge Butter, cut into pieces
3 Tablespoons sugar
1/3 cup semisweet chocolate chips
1 1/3 cups sugar
1 cup (2 sticks) Challenge butter
1 cup whipping cream
1/3 cup light corn syrup
2 1/2 cups chopped walnuts
2 Tablespoons semisweet chocolate chips, melted
1. Preheat oven to 350 F. To prepare crust, combine flour, 1/2 cup butter and 3 Tablespoons sugar in a food processor or medium bowl. Pulse or mix with a pastry blender until dough resembles coarse crumbs. Press into the bottom of a foil-lined 9-inch square pan. Bake until lightly browned, about 20 minutes. Remove from oven and sprinkle with chocolate chips; let stand 2 minutes, then spread chocolate over crust.
2. To prepare filling, place 1 1/3 cups sugar in a large heavy saucepan; stir over low heat until melted and caramel colored, about 20 minutes. Stir in 1 cup butter, cream and corn syrup. Mixture will bubble up and clump together. Simmer over medium-low heat stirring frequently until mixture is smooth and reaches 234 to 240 F (soft ball stage) on a candy thermometer, about 35 minutes. Remove from heat and stir in walnuts. Immediately pour over crust. Drizzle with melted chocolate. Refrigerate until firm. Use foil to lift out of pan; transfer to cutting board. Cut into 16 squares.