1.Preheat the oven to 350° Fahrenheit. Line two baking sheets with parchment paper or silicon baking mats and set aside. 2.In the bowl of an electric mixer, beat the egg whites until stiff peaks form. Gradually add about half of the sugar, gently sprinkling it over the whipping egg whites. Add the vanilla extract, then continue gradually adding the remaining sugar, until the meringue is very shiny and stiff. Gently fold in the chocolate chips and toffee bits. 3.Spoon one tablespoon of meringue onto the lined baking sheets, then repeat with the rest of the meringue, leaving 1-inch of space between cookies. Place the baking sheets in the preheated oven and then turn the oven off. Leave the cookies in the oven overnight (or for a minimum of 6 hours), undisturbed (DO NOT OPEN THE OVEN DOOR!). Gently remove the cookies from the baking sheets and store in an airtight container. Toffee Bits: 4.Line a baking sheet with foil or a silicone baking mat and set aside. 5.Combine the butter, sugar, vanilla, and salt in a heavy 2-quart saucepan. Cook over high heat, stirring constantly with a clean, dry, wooden spoon until the butter is melted. Continue cooking and stirring for 5 to 7 minutes, or until the candy is the color unblanched almonds. Immediately pour the candy, without scraping the saucepan, onto the lined baking mat. Cool completely. 6.Break the cooled toffee into pieces: Break the toffee into large pieces and place them in a sturdy plastic bag. Using a rolling pin/meat tenderizer/other heavy object, pound the toffee until broken into small pieces. Store the pieces in an airtight container until ready to use.