Optional chocolate decoration:
Split vanilla beans lengthwise and scrape seeds into a large heavy-bottomed saucepan, along with scraped out pods. Place remaining ingredients in saucepan and place over high heat. Cook to a caramel color while continuously stirring with a wooden spoon. The mixture will become very thick. Pull out the vanilla beans and set aside. Lightly spray the work surface with vegetable cooking spray. If you would like to use metal rulers so the brittle will be rolled to an even thickness, set them into place now. Immediately pour the mixture onto the marble or granite slab (you can also use a parchment paper lined baking sheet). Place a piece of parchment paper over the hot brittle and use a rolling pin to roll the peanut brittle into a 3/8-inch thick flat layer. Use a sharp chef's knife to partially cut the brittle while it is still warm. Allow it to cool completely before coating it with chocolate. It is ready to eat now or you can add chocolate to the outside of the brittle.
To cover with chocolate: You can use a variety of methods to apply chocolate to the brittle. You could simply place some chocolate into a cornet and drizzle the chocolate over the cool brittle. You could also use a dipping fork to dip each piece of brittle in the chocolate. Whatever method you use, allow the chocolate to set and it is ready to serve.
From Dessert Circus, Extraordinary Desserts You Can Make At Home by Jacques Torres
The Cornet: A cornet is a small piping bag made from parchment paper. It is usually used to make fine decorations.
Cut an 8 by 12 by 14 1/2-inch triangle from a sheet of parchment paper. Hold the middle of the long side of the triangle between two fingers of 1 hand. Take the tip of the triangle on the short, wide end and roll it toward the other tip of that same end while simultaneously pulling it in an upward motion. The tip of a cone will form where your thumb and finger hold it on the long side.
Release your grip from the long side, so that you are now holding the 2 corners where they meet. The paper will already resemble a partially formed cone.
Roll the remaining tail until it is completely rolled into a cone. There will be 1 point sticking up from the open end. Fold it inside toward the center, and crease the fold. Now you should have a cornet. To close the cornet once it has been filled, fold it away from the seam; this will keep the seam from opening. Use a pair of scissors or a sharp paring knife to cut an opening at the tip of the cornet to the desired size.