01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, cocoa powder, baking soda, salt, and cinnamon. Stir in the rolled oats.
03 - In a large bowl, beat butter, brown sugar, and granulated sugar until light and fluffy, about 2 minutes.
04 - Add eggs one at a time, beating well after each addition, then mix in vanilla extract.
05 - Gradually add dry ingredients to wet mixture, stirring just until combined.
06 - Gently fold in raisins and optional chocolate chips.
07 - Drop rounded tablespoons of dough onto prepared baking sheets, spacing about 2 inches apart.
08 - Bake for 10 to 12 minutes, until edges are set but centers remain soft.
09 - Cool cookies on baking sheets for 5 minutes, then transfer to a wire rack to cool completely.