STIR together first 3 ingredients in a medium bowl; cut in butter with a pastry blender until crumbly. (Mixture will look very dry.) Gently press mixture with hands, working until blended and smooth (about 2 to 3 minutes).
SHAPE dough into 2 (4-inch-long)logs. Wrap in plastic wrap, and place in an airtight container. Chill 8 hours, or freeze up to 3 months. (Thaw overnight in refrigerator).
CUT into 1/4-inch-thick slices, and place on a lightly greased sheet. Brush with milk.
BAKE at 350 for for 12 to 15 minutes or until lightly browned. Freeze up to 1 month, if desired.
NOTE:Dough may be rolled into a 10 x 7-inch (1/4-inch-thick) rectangle on a lightly floured surface. Cut lengthwise into 8 strips and crosswise into 4 strips, using a pastry wheel or knife, and forming 32 squares. Place cheese squares on a lightly greased baking sheet, and bake immediately.