Heat oven to 350° F. In large bowl, combine flour and sugar. Cut in butter with a pastry blender until consistency ofcornmeal. Reserve 1/2 cup of this mixture. In a small bowl, beat eggs; add milk, salt, baking powder, and vanilla. Add to dry mixture and beat until smooth. Do not overbeat. Pour batter into a greased 8-inch square baking dish. Sprinkle top with reserved 1/2 cup dry mixture and sprinkle with nuts. Bake 20 to 25 minutes.
Note: For high altitude, use only 1 1/2 teaspoons baking powder. Bake at 375° F for 25 to 30 minutes.