Preheat oven to 350°F (175°C). Lightly grease an 8x8 baking dish with non-stick spray.
In a large bowl, stir together the flour, half of the sugar, and a pinch of salt. Mix in half of the melted butter until mixture resembles coarse crumbs. Lay the mixture evenly into the baking dish and press in firmly.
Bake for 15 minutes in the oven.
While the crust is baking, prepare the filling. In a large bowl, mix together the egg, molasses, vanilla, remaining melted butter and sugar until smooth. Stir in the pecans. Spread the filling evenly over the crust as soon as it comes out of the oven.
Bake for 15 to 20 minutes in the oven, or until set. Allow to cool completely before slicing into squares.