Instructions

• Line a 15 x 10-inch (jellyroll) baking pan with aluminum foil and lightly spray the foil with cooking spray; set the pan aside.
• In a heavy-bottomed saucepan, combine 2 cups (1 pound) butter, 2 cups granulated sugar, and 1 tsp salt.
• Clip a candy thermometer to the side of the saucepan (making sure the bulb is in the mixture but not touching the pan). Melt the butter over medium-high heat, stirring until the sugar is completely dissolved, then continue cooking and stirring until the mixture reaches 290°F.
• Remove the saucepan from the heat, stir in 1 tsp vanilla extract and 3/4 cup slivered almonds, then immediately pour the hot toffee into the prepared pan. Use a heatproof spatula to spread the toffee evenly.
• Place the pan on a wire rack and allow the toffee to cool at room temperature until firm to the touch.
• While the toffee cools, place 3/4 cup butterscotch chips in a small microwave-safe bowl and 3/4 cup milk chocolate chips in a separate microwave-safe bowl. Divide 1 1/2 tsp shortening between the two bowls (use half the shortening in each bowl).
• Microwave each bowl on high in 30-second intervals, stirring between intervals, until the chips in that bowl are fully melted and smooth.
• Once the toffee is cooled and firm, use an offset spatula to spread the melted butterscotch evenly over the toffee, then spread the melted milk chocolate evenly on top of the butterscotch (or arrange as desired).
• Refrigerate the pan for at least 30 minutes to allow the chocolate layers to set.
• Remove the foil from the pan, break the toffee into pieces, and serve.