In a medium mixing bowl, use an electric mixer to beat softened butter with sugars until smooth and light (about 1 ½ min.). Add egg and vanilla; beat until well combined (about 30 sec.). In a separate small mixing bowl, whisk together flour, soda, salt, baking powder and oats; mix into butter and egg mixture just until you can no longer see white. Stir in raisins by hand. Drop 18 evenly sized rounded spoonfuls 2" apart on 2 parchment-lined baking sheets. Bake in a preheated 350° oven until just set (12-13 min.), turning pans halfway through. Remove from oven; cool on pan for 2 min., then cool completely on wire racks.