How to Make It
Make the piecrust In a food processor, pulse the flour with the sugar and salt. Add the butter and pulse until it is the size of small peas. Add 1/4 cup of ice water and pulse until the dough is evenly moistened. Gradually add more water if needed. Turn out the dough onto a work surface and knead 2 to 3 times, just until it comes together. Form into a disk, wrap in plastic and refrigerate until firm, about 1 hour.
On a lightly floured work surface, roll out the dough to a 12-inch round; transfer to a 9-inch pie plate. Fold the edge of the dough under itself and crimp the edge. Freeze the piecrust for at least 2 hours or overnight.
Preheat the oven to 375°. Line the piecrust with parchment paper and fill with pie weights or dried beans. Bake for about 25 minutes, or until lightly browned around the edge. Remove the paper and weights and bake until the bottom is lightly browned, about 10 minutes. Let cool completely.
Meanwhile, make the filling Reduce the oven temperature to 350°. Spread the pecans on a rimmed baking sheet and toast until fragrant, 8 to 10 minutes. Let cool completely.
In a small skillet, cook the dates in the brewed espresso over moderate heat, stirring, until very soft, 3 to 5 minutes. Scrape the mixture into a small bowl and wipe out the skillet.
Add the butter to the pan and cook over moderate heat, swirling, until the milk solids turn a deep golden brown, about 5 minutes. Let cool slightly.
In a large bowl, whisk the brown sugar with the golden syrup, espresso powder and salt. Whisk in the eggs, then gradually whisk in the brown butter until the filling is smooth.
Set the pie plate on a rimmed baking sheet. Spread the espresso dates in the crust and scatter the pecans on top. Pour the filling over the pecans. Bake for about 1 hour and 15 minutes, or until the filling is set around the edge and slightly jiggly in the center. Transfer the pie to a rack and let cool completely. Serve with whipped cream.