Place sugar, eggs, milk, margarine, flour, vanilla, and 1 cup chopped pecans in a blender. If blender will not contain the entire mixture, reserve some of the milk to add later. Pour mixture into greased miniature muffin pans, about half full. Place a pecan half on top of each pie. Bake in a preheated 300 oven for 30 to 35 minutes or until a knife in the center comes out clean.