Instructions

• Spray a 9-inch square baking dish with cooking spray and line it with parchment paper, leaving an overhang on two opposite sides for easy lifting.
• Spread 1 cup coarsely chopped pecans in a single layer on the parchment-lined dish.
• In a heavy-bottomed 3-quart pot, combine 1 cup unsalted butter, 1 cup granulated sugar, and ½ teaspoon kosher salt.
• Heat the mixture over medium-low, stirring frequently until the sugar dissolves and the butter melts.
• Bring the mixture to a boil, then continue boiling while stirring occasionally (slow, even strokes) until it reaches 290°F–300°F on a candy thermometer (hard-crack stage). The mixture will be very hot—use caution.
• Remove the pot from the heat and gently stir in 1 teaspoon vanilla extract.
• Carefully pour the hot toffee evenly over the chopped pecans in the prepared dish.
• Let the toffee sit undisturbed for a few minutes (about 2–3 minutes) so it begins to set, then evenly sprinkle 1 cup milk chocolate chips over the top.
• Cover the dish with foil and let sit 5 minutes, or until the chocolate chips have softened.
• Remove the foil and use an offset spatula (or a regular spatula/knife) to gently spread the softened chocolate into an even layer.
• Refrigerate the dish until the toffee is completely firm, at least 2 hours.
• Lift the toffee from the dish using the parchment overhang and place it on a cutting board or solid surface.
• Use a knife to cut or gently break the toffee into pieces.
• Store the toffee in an airtight container in a cool place.