Preheat your oven to 180C/350F and grease a 20cm square baking pan.
Line the pan with parchment paper, leaving an overhang for easy removal.
In a bowl, mix half the melted dairy-free butter, half the brown sugar, and a portion of the salt.
Stir in the flour until a cohesive dough forms.
Press the mixture evenly into the bottom of the prepared pan.
Bake the base for 20 minutes and remove from the oven to cool slightly.
While the base cools, whisk together the remaining melted butter, remaining brown sugar, remaining salt, eggs, maple syrup, and vanilla extract.
Stir in the toasted pecans until well coated.
Pour the pecan mixture over the partially baked crust.
Return to the oven and bake for an additional 20-25 minutes until the topping is set.
Allow to cool completely in the pan before lifting out by the parchment paper and slicing into squares.