Preheat oven to 350°F (175°C) and line two baking sheets with parchment paper.

In a mixing bowl, cream together softened butter, brown sugar, and granulated sugar until light and fluffy.

Beat in the egg and vanilla extract until fully combined.

In another bowl, whisk together rolled oats, flour, baking soda, cinnamon, and salt. Gradually add this mixture to the wet ingredients until just combined.

Gently fold in the raisins until evenly distributed.

Drop spoonfuls of dough onto prepared baking sheets about two inches apart.

Bake for 10-12 minutes or until edges are golden but centers remain soft. Allow cooling before serving.