MAKE THE TOFFEE
• Place four pieces of parchment paper on a flat work surface and grease the parchment with butter or unflavored cooking spray (canola works well). You will pour the toffee onto these four sheets. Set aside four more sheets of parchment paper (greased on one side) to put on top of the toffee. (You can also use non-stick silicone baking mats, like Silpats in lieu of parchement).
• Combine butter, sugar, water, maple syrup, and glucose in a heavy bottomed saucepan.
• Make sure the vanilla and salt are measured out before you begin cooking the toffee. They will be added as soon as the toffee has reached the correct temperature.
• Cook sugar mixture, stirring constantly, until it reaches 298°F.
• Quickly stir in vanilla and salt and pour toffee onto the four pieces of parchment.
• Place the remaining four pieces greased side down on top of the toffee and use a rolling pin to roll the toffee to about ¼-inch thickness.
• Allow toffee to cool to room temperature. Store toffee without chocolate in an airtight box, or use an offset spatula to coat both sides of the toffee in tempered semisweet chocolate.
• Break toffee into shards and serve.