This easy and amazing butter toffee recipe is the ultimate homemade holiday gift! Covered in milk chocolate or dark chocolate, it's crunchy, creamy, and chocolatey. Store at room temperature for up to 2 weeks!
Position a rack in the center of your oven. Preheat the oven to 350 degrees (F).
Lightly brush the bottom of a large rimmed baking sheet with vegetable oil. Lightly grease both sides of an offset spatula with vegetable oil. Set aside until needed.
Place almonds on a separate baking sheet and bake for 8 to 10 minutes, tossing halfway, until almonds are lightly golden (you don’t want dark brown spots). Cool for 10 minutes. Transfer nuts to a cutting board and roughly chop. Set aside until needed.
In a medium-sized deep saucepan, combine the butter, salt, rum, water, sugars, and corn syrup.
Cook over medium-heat, stirring occasionally, until the butter has completely melted. Increase the heat to medium-high and continue cooking, without stirring, until the mixture registers 300 degrees (F) on a candy thermometer.
Remove from heat and immediately stir in the baking soda and 1 and ¼ cups of the chopped almonds, stirring with silicone spatula until well combined.
Immediately pour the toffee onto the prepared baking sheet and, using the prepared offset spatula, spread it into a 10x12 inch rectangle.
While the toffee is hot, sprinkle the chocolate chips over it in an even layer. Allow the chocolate to sit for 2 minutes. Then, using a small offset spatula, spread the chocolate over the toffee, covering it completely.
Sprinkle with remaining chopped almonds and flaky sea salt, if using.
Refrigerate for 1 hour, then let stand at room temperature until chocolate is completely set. Holding the toffee with a piece of wax paper, break it into rough pieces. Store in an airtight container, in the refrigerator, for up to 1 week.