Preheat oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper, leaving overhang on sides.
In a medium bowl, combine melted butter, flour, sugar, and salt until crumbly. Press mixture firmly into the bottom of the prepared pan. Bake for 15 minutes or until lightly golden; let cool completely.
In a large bowl, whisk together brown sugar, corn syrup, heavy cream, eggs, and vanilla until smooth. Stir in chopped pecans.
Pour filling over cooled crust. Return to oven and bake for 20–25 minutes, or until center is set and edges are bubbly.
Cool completely in pan on a wire rack, then refrigerate for at least 2 hours before cutting into bars.
Notes
For best results, allow bars to chill thoroughly before slicing to ensure clean cuts.