In a bowl, with an electric mixer on medium speed, beat butter and sugar until smooth. Beat in egg.
In another bowl, mix flour, baking soda, and oats. Stir or beat into butter mixture until well blended. Stir in raisins.
Divide dough into seven equal portions. Pinch each portion into a 12-inch-long rope and evenly space two or three ropes across buttered or cooking parchment-lined 12- by 15-inch baking sheets. Flatten ropes to make 2-inch-wide strips.
Bake in a 350° oven until strips are lightly browned, about 10 minutes; if baking more than one pan at a time, switch pan positions halfway through baking.
Let strips cool on sheets for about 2 minutes, then cut diagonally into 1-inch-wide pieces. Let cool completely on sheets.
Note: Nutritional analysis is per cookie.