Preheat the oven to 350°F (175°C). Lightly grease a 9-inch square baking pan and line it with parchment paper, leaving some overhang for easy removal.

In a bowl, mix the flour, softened butter, sugar, and salt until it resembles soft crumbs that hold together when pressed. Press it evenly into the bottom of the prepared pan.

Bake the crust for 12 to 15 minutes, until the edges are lightly golden. Let it cool for a few minutes.

Melt the chocolate chips and butter in a saucepan over low heat, stirring until smooth.

Remove from heat and whisk in the brown sugar.

Let the mixture cool slightly, then whisk in the eggs one at a time, followed by the vanilla and salt until smooth.

Fold in the chopped pecans and heavy cream until well combined.

Pour the chocolate pecan mixture over the crust and spread evenly.

Bake for 30 to 35 minutes, until the center is set but slightly soft.

Allow to cool at room temperature, then refrigerate for at least 2 hours.

For the topping, melt the chocolate chips with heavy cream until smooth.

Drizzle over the chilled dessert and sprinkle with chopped pecans.

Let the topping set for a few minutes, slice into 12 squares, and serve chilled or at room temperature.