Preheat oven to 350°. Line a 13×9-inch baking pan with parchment paper, letting excess extend over sides of pan.
In a large bowl, beat 1 cup butter and ⅔ cup brown sugar with a mixer at medium speed until creamy, 3 to 4 minutes, stopping to scrape sides of bowl. Add flour and salt, beating until crumbly. Press mixture into bottom of prepared pan.
Bake for 20 minutes.
In a medium saucepan, heat corn syrup, cream, remaining ½ cup butter, and remaining 1 cup brown sugar over medium heat until sugar is dissolved, about 1 minute. Remove from heat. Stir in pecans and vanilla. Pour mixture over prepared crust, spreading to edges. Sprinkle with chocolate.
Bake for 20 minutes. Let cool completely. Using excess parchment as handles, remove from pan, and cut into bars.
Recipe by Louisiana Cookin' at https://louisianacookin.com/chocolate-pecan-pie-bars/