Grease a 9×12 or 9×9 metal baking dish and line it with parchment paper, avoiding greasing the top of the parchment.

Heat whole almonds over medium heat in a skillet for about 5-7 minutes, stirring every 30 seconds, or roast them in an oven preheated to 325°F for about 10-15 minutes.

Coarsely chop half of the almonds and spread them evenly into the prepared baking pan, setting the remaining nuts aside.

In a large heavy saucepan, combine the butter, sugar, vanilla extract, and sea salt. Set over medium heat and stir constantly until the butter melts and the mixture begins to boil.

Keep stirring until the mixture reaches a deep caramel color, which typically takes 8 to 10 minutes, aiming for a temperature of 300°F.

Immediately pour the toffee mixture into the prepared pan, tilting it to spread evenly over the nuts.

While the toffee is still hot, sprinkle chocolate chips on top and wait about 2 minutes for them to soften. Spread melted chocolate evenly across the surface and sprinkle with the reserved chopped almonds.

Let your toffee cool for at least 2 hours at room temperature until the chocolate is fully set.

Cut or break the toffee into pieces to serve and store leftovers in an airtight container at room temperature for up to a week.