Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a large bowl cream butter brown sugar and granulated sugar until light and fluffy.
Add eggs one at a time mixing well after each addition then mix in vanilla extract.
In another bowl whisk together flour baking soda cinnamon and salt.
Gradually add dry ingredients into the wet mixture and mix until combined.
Fold in rolled oats raisins and optional walnuts until evenly distributed.
Scoop tablespoon-sized portions of dough onto prepared baking sheet leaving space between cookies.
Bake for 10–12 minutes until edges are golden and centers remain slightly soft.
Allow cookies to cool on the baking sheet for a few minutes then transfer to a cooling rack.