Chop the toasted almonds and place 1 ½ cups in a small bowl, and the remaining 1 cup in another small bowl.
Unwrap the chocolate bars and set aside.
In a medium or large saucepan, melt the butter over medium heat. Once the butter stops foaming, add the brown sugar and stir. Once the mixture bubbles, place in the candy/instant-read thermometer and stir constantly until the mixture reaches 300°F.
Remove the mixture from the heat and add the vanilla and 1 ½ cups of toasted, chopped almonds. Pour mixture into the buttered pan and smooth the mixture so it sits in the pan evenly.
Place the chocolate bars on top of the mixture and let it sit for about 4 minutes so the chocolate has a chance to melt. This will make spreading easier (you’ll know it’s ready to spread when it gets all nice and shiny).
Using the back of a spoon spread the chocolate in an even layer. Sprinkle the remaining 1 cup of toasted almonds over the chocolate and gently press it in.
CHILL AND FINISH:
Cover and chill the Almond Roca Brittle for at least 4 hours before breaking it apart (I personally like to chill it overnight).
Use a knife to break the brittle apart.
Notes
This recipe makes about 6 cups of almond roca candy.