These soft, chewy oatmeal cookies with plump raisins are the best oatmeal cookie recipe on the planet!
Preheat oven to 365 degrees. In a large mixing bowl, cream butter, brown sugar, and sugar for 4 minutes or until light and fluffy. Scrape the sides of the bowl halfway through to ensure even mixing.
Add eggs and vanilla and mix for 1 minute longer.
Stir in flour, rolled oats, cornstarch, baking soda, and salt. Add cinnamon (if using). Fold in raisins.
Drop onto a light-colored baking sheet. Bake for 9-11 minutes or until edges start to turn a light golden color. Don't overbake. The cookies will continue to bake once you remove them from the oven. I prefer to under-bake rather than over-bake.
Let cool on the baking sheet for at least 5 minutes.