Line a jelly roll pan with parchment paper and place a layer of mini pretzels all along the bottom. Optionally, you can also roughly crush 3 – 4 mini pretzels and sprinkle over the bottom as well to cover any large holes between each pretzel. Set aside.

In a thick bottomed saucepan, add the butter, sugar, water, and salt. Heat on medium for about 8 minutes, or until a candy thermometer reads 280 degrees F. Gently clean the sides of the saucepan as it cooks with a wet pastry brush to prevent any crystallization.

As soon as the thermometer reads 280 degrees F, quickly stir in the vanilla and pour the caramel over the pretzels. If the pretzels move a lot while you pour, you can quickly go back in with a skewer to reposition any pretzels that moved.

Allow the toffee to sit untouched for about 5 – 8 minutes to allow the top to harden slightly. Top with the chocolate and allow the chocolate to sit on the toffee for about 3 – 4 minutes before using an offset spatula to spread the chocolate.

Crush any remaining pretzels over the chocolate while it is still melted. Sprinkle the flaky Maldon salt over the chocolate.

Allow to sit for until it reaches room temperature – about an hour and a half. You can also store the toffee in the refrigerator or freezer for a few minutes. Once the toffee is cooled competely, use a knife to roughly chop the toffee.

Store in an airtight container for up to two weeks.