Preheat Oven and Prepare Baking Sheets: Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper or lightly grease them.
Cream Butter and Sugars: In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until the mixture is light and fluffy.
Add Eggs and Vanilla: Beat in the eggs, one at a time, followed by the vanilla extract, ensuring they are fully incorporated.
Combine Dry Ingredients: In a separate bowl, whisk together the flour, baking soda, cinnamon, and salt.
Mix Dry Ingredients into Wet Mixture: Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Fold in Oats and Raisins: Gently fold in the rolled oats and raisins, making sure they are evenly distributed throughout the dough.
Shape the Cookies: Drop rounded tablespoons of dough onto the prepared baking sheets, spacing them about 2 inches apart.
Bake: Bake in the preheated oven for 10-12 minutes, or until the edges are golden brown but the centers are still soft.
Cooling: Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.