Preheat the oven to 350 degrees Fahrenheit.
Using an electric mixer with the paddle attachment on medium-high speed, beat the butter, brown sugar and granulated sugar until light and fluffy. With the mixer on low, add the eggs and vanilla and mix well.
Whisk the flour, baking powder and cinnamon together in a large bowl. With the mixer on low, slowly add the dry ingredients to the butter mixture. Add the oats and raisins and mix until just incorporated.
Using a small ice cream scoop (I use 1.5 inch), or a Tablespoon, drop mounds of dough onto baking sheets lined with parchment paper, spacing them a few inches apart. Flatten the cookie dough slightly with a dampened hand. Bake until lightly browned, about 12 to 15 minutes. Transfer the cookies to a baking rack to cool.