Preheat your oven to 350°F (175°C).

In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until smooth.

Add the egg and vanilla extract to the mixture and beat until well combined.

In a separate bowl, mix the rolled oats, flour, baking soda, salt, and cinnamon.

Gradually combine the dry ingredients with the wet mixture, stirring until just mixed.

Fold in the raisins until evenly distributed.

Drop rounded tablespoons of dough onto a baking sheet lined with parchment paper.

Bake in the preheated oven for 12-15 minutes until the edges are lightly golden.

Remove from the oven and let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack.