Preheat the oven to 375°
For the crust, combine the flour, sugar and salt. Using a pie cutter, two forks or your hands, cut in the butter until the mixture resembles coarse crumbs. Add the milk, a tablespoon at a time, just until it holds together when you squeeze a clump of the dough in your hands.Pat the mixture firmly and evenly into a 9 x 13 pan and bake for about 15 minutes.Set aside.
While the crust is cooking, make the filling. Stir together the flour, brown sugar and butter until sandy.Set aside.
Whisk together the molasses and corn syrup, add the hot coffee and baking soda, whisk in until smooth. Add the beaten eggs, vanilla and salt until combined thoroughly.
Sprinkle the reserved flour and brown sugar mixture over the cooked crust.
Pour the molasses mixture evenly over and toss the pecans over the top.
Place in the upper third of the oven. Bake for 10 minutes and reduce temperature to 350°.Bake for another 25 minutes or until the center is no longer jiggly.
Cool and cut into bars. Sprinkle with sifted powdered sugar if you like.
* You can skip the coffee and use hot water if you prefer.