Preheat your oven to 350°F (175°C). Line a 9x13 inch metal baking pan with parchment paper, leaving a 2-inch overhang on the sides for easy removal later.

In a medium bowl, whisk together the flour, light brown sugar, and salt. Pour in the melted butter and vanilla extract, stirring with a spatula until a soft, crumbly dough forms.

Press the dough evenly and firmly into the bottom of the prepared pan. Bake for 18-20 minutes until the edges are lightly golden. Remove from the oven and keep the oven at 350°F.

While the crust bakes, whisk the eggs in a large bowl until smooth. Add the pure maple syrup, dark brown sugar, melted butter, vanilla extract, and sea salt, whisking until completely combined and glossy.

Fold the pecans into the maple mixture, then pour the filling evenly over the warm pre-baked shortbread crust.

Bake for 25-28 minutes until the edges are set and the center has just a slight jiggle when gently shaken.

Cool completely at room temperature for 1 hour, then chill in the refrigerator for at least 1 hour before lifting out with the parchment paper and slicing into 16 neat squares.