Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.
In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.
Beat in the eggs one at a time, then stir in the vanilla extract.
In another bowl, whisk together the flour, baking soda, salt, and cinnamon.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Stir in the oats and raisins until evenly distributed.
Drop rounded tablespoons of dough onto the prepared baking sheets, spacing them about 2 inches apart.
Bake in the preheated oven for 10-12 minutes, or until the edges are golden brown.
Allow the cookies to cool on the baking sheets for a few minutes before transferring them to wire racks to cool completely.
Variations & Tips
For a nutty twist, add 1/2 cup of chopped walnuts or pecans to the dough. If you prefer a bit of spice, try adding a pinch of nutmeg or cloves. For those who enjoy a touch of citrus, a teaspoon of orange zest can brighten up the flavor. You can also substitute the raisins with dried cranberries or chopped dried apricots for a different fruity taste.