Instructions

• Preheat oven to 350°F. Line a half-sheet baking pan (18×13 inches) with parchment paper or aluminum foil.
• Spread the 1 1/2 cups roughly chopped almonds in a single layer on the prepared pan. Roast in the oven 5 minutes, watching closely so they do not burn. Remove pan from oven.
• Immediately sprinkle 1 cup of the semi-sweet chocolate chips evenly over the hot almonds, then sprinkle 1 teaspoon cinnamon evenly over the chocolate chips. Set the pan aside.
• Place a large, heavy-bottomed stockpot on the stove (do not use a small saucepan). Add 1 pound salted butter, 1/4 cup Karo corn syrup, 1/2 teaspoon salt, 2 1/2 cups sugar, and 1 cup water. Stir to combine.
• Clip a candy thermometer to the pot so the tip is submerged but not touching the bottom. Bring the mixture to a full boil over medium-high heat, stirring frequently until the sugar is dissolved. Continue cooking, stirring frequently and watching the thermometer, until the mixture reaches 300°F (hard-crack stage). This can take about 12–16 minutes from boiling; watch closely as it approaches 275°F because the temperature can rise quickly. Take care—sugar will be extremely hot.
• As soon as the toffee reaches 300°F, remove the pot from the heat and immediately pour the hot toffee evenly over the prepared almonds and chocolate on the baking pan. Use a heatproof spatula to spread the toffee into an even layer if needed.
• Immediately sprinkle the remaining 2 cups semi-sweet chocolate chips evenly over the hot toffee. Let sit 1–2 minutes until the chips soften, then use a spatula to spread the melted chocolate into an even layer.
• Immediately sprinkle the 1/2 cup finely chopped pecans evenly over the melted chocolate. Allow the toffee to cool completely at room temperature until the chocolate is set and the toffee is firm.
• Once cooled and hardened, break the toffee into pieces. Store in an airtight container at room temperature.