Coat an 8-inch square baking dish with nonstick cooking spray.
In a heavy saucepan - bring the butter, heavy cream, brown sugar, white sugar, & salt to a boil over medium heat, stirring frequently. Allow to boil for 5 minutes, stirring constantly. Remove pot from the heat.
Stir in the pecans and vanilla. Add the confections' sugar & stir until smooth. Spread the mixture into the baking dish.
Allow to cool to room temperature then cut into 1-inch squares. Store in an airtight container.