Spray a 9 inch square baking dish with cooking spray and line with parchment paper.
Spread chopped pecans in a single layer on top of parchment paper.
Add butter, sugar, and salt to a 3 quart pot.
Bring to a boil over medium low heat, stirring frequently. Once candy is boiling, stir occasionally until reaching 290 to 300º or until "hard crack" on a candy thermometer.
Remove from heat and stir in vanilla.
Pour over chopped pecans.
Let sit to harden. Sprinkle chocolate chips on top. When chocolate has softened, spread chocolate into an even layer.
Place in refrigerator at least 2 hours.
Lift parchment out of dish and place on cutting board. Break into smaller pieces.
Store in airtight container.