Preheat oven to 350F. Toast the whole pecans on a baking sheet for 6-8 minutes or until golden brown and fragrant. Remove, let cool slightly and then roughly chop.
Cover a large baking sheet with foil, making sure there is over hang on the sides. Spray with cooking spray and set aside.
In a heavy bottomed sauce pot melt the butter, sugar, water and salt over medium heat. Stirring occasionally, cook until the mixture reaches 305F (hard-crack stage). Remove from heat and stir in the vanilla and chopped pecans.
Working quickly, pour the mixture onto the prepared cookie sheet and spread out into a flat even layer using a silicone spatula. Cool at room temperature for 30-40 minutes or until hard.
In a double boiler, gently melt the chocolate making sure not to scortch it. Pour the chocolate over the hardened toffee, covering fully.
Let set for 5 minutes and then sprinkle liberally with the salt.
Let cool fully, at room temperature for 1 hour or until the chocolate has hardened. Break into medium sized pieces. Store in an airtight container for up to 1 month.
Recipe Courtesy of Megan Mitchell