1. For crust, stir together the 2/3 cup flour and 1/2 cup brown sugar.
2. Using a pastry blender, cut in the 1/3 cup butter until pieces are the size of fine crumbs.
3. Stir in the 1/2 cup finely chopped pecans.
4. Press mixture into an ungreased 9x9 pan; set aside.
5. For brownie layer, in a medium saucepan over low heat, melt the 1/4 cup butter, shortening and chocolate, stirring until smooth.
6. Remove from heat.
7. Cool slightly (about 5 minutes).
8. Stir in 1/2 cup brown sugar and granulated sugar.
9. Add the eggs, one at a time, beating after each addition just until combined.
10. Stir in the 1/4 cup coffee liqueur, the 2 tablespoons milk, vanilla, and salt.
11. Add the 1/2 cup flour and stir just until moistened.
12. Pour batter over crust.
13. Bake in a 350° oven for 20 to 25 minutes or until toothpick inserted in center comes out clean with crumbs clinging to it.
14. Cool brownies in pan on wire rack.
15. For frosting, stir together the powdered sugar, melted butter, and the 1 teaspoon coffee liqueur.
16. Stir in enough of the 1 to 2 tablespoons milk to make a spreading consistency.
17. Spread over cooled brownies. Cut into bars.