In a stand mixer, combine the butter, brown sugar, salt, and flour. Mix with the paddle attachment until a smooth, sticky dough forms. Press evenly into the prepared pan. Chill for 1 hour for easier handling.

Bake the crust for 20 minutes, until the edges are just lightly golden. Remove from the oven and set aside.

In a wide saucepan, combine the butter, dark brown sugar, maple syrup, and cream. Heat over low until it reaches a gentle boil.

Whisk the eggs lightly in a separate bowl. Gradually pour the hot maple mixture into the eggs in a thin stream, whisking constantly. Continue whisking for 2 minutes after all syrup is incorporated. Return to low heat for 2 more minutes, whisking continuously.

Remove from heat and stir in the pecans until evenly coated. Pour over the pre-baked crust and spread gently with a spoon.

Bake for 30 minutes, until the topping is set. Cool at least 2 hours, or freeze for 1 hour to speed cooling.

Lift from the pan using the parchment. Cut into squares, sprinkle salt, and serve. Store in an airtight container in the refrigerator for up to 5 days.