Preheat oven to 350°F. Line a 10x15-inch jelly roll pan (or a cookie sheet with 1” sides) with foil and spray with nonstick cooking spray.

Place graham crackers in an even layer on the prepared pan, breaking some to make them all fit. Set aside.

Place butter in a medium saucepan and melt over low heat. Add brown sugar and water and stir to combine. Place a candy thermometer in the pan and then cook over medium-low heat, not stirring, until the mixture reaches 255°F. If you don’t have a candy thermometer you can also check it often with an instant read thermometer.

Once it reaches 255°F, immediately remove the pan from the heat and stir in vanilla and salt. Pour and spread evenly over the graham crackers. Bake for 5 minutes.

Remove the toffee from the oven and sprinkle evenly with chocolate chips. Bake an additional 2 minutes.

Place peanut butter in a microwave safe bowl and heat for 15-20 seconds, or until it’s pourable. When the toffee comes out of the oven, the chocolate chips will be melted and spreadable. Spread the chocolate even with a knife and then drizzle the peanut butter over the top and swirl with the knife or the back of a wooden spoon. Chill to harden, then break into pieces.

Store in an airtight container for up to one week.