Line a small square pan or loaf pan with parchment paper and spread out 1/4 cup of the chopped almonds over the bottom. Set aside.
In a small saucepan, combine your butter and sugar. On low heat, heat up until the butter has melted and the sugar has dissolved. Stirring regularly, once the mixture begins to bubble, add your candy thermometer into the center of the mixture. Continue to stir every 30 seconds, until the thermometer reaches 300F (hard crack). Remove from the heat.
Continue stirring continuously to ensure the butter and sugar do not separate. Pour into the lined pan and let sit for 5 minutes.
After 5 minutes, top with your chocolate chips evenly over the top. Cover the pan with tin foil and let sit for 5 minutes. After 5 minutes, remove the tin foil. Using a rubber spatula, spread out the chocolate evenly over the toffee. Once spread, top with remaining chopped almonds. Refrigerate for at least 2 hours, or overnight. Once set, use a sharp knife and slice into pieces.
TO STORE: Almond Roca can be stored at room temperature, in a sealed container. You can store homemade Almond Roca at room temperature for at least 2 weeks. You can also refrigerate it and it will keep for up to 2 months. TO FREEZE: Wrap pieces in parchment paper and place them in a ziplock bag or shallow container. They can be kept frozen for up to 6 months.