Preheat the oven to 350°F (175°C). In a stand mixer fitted with the paddle attachment, cream together the white sugar, brown sugar, butter, vanilla, and egg until the color has lightened.
In another bowl, whisk together the flour, baking powder, baking soda, and salt.
Gradually add the flour mixture to the creamed mixture, about 1/4 cup at a time, scraping the sides of the bowl as you go. Mix until well combined, and the dough should be smooth and soft but not sticky.
Pour in the old fashioned oats while the mixer stirs at a medium-low speed. Add 1/2 cup of oats at a time, followed by the raisins, a few tablespoons at a time, ensuring they are evenly distributed throughout the dough.
Roll the dough into 1-inch balls using your hands and arrange them onto a cookie sheet lined with parchment paper.
Bake for 10-12 minutes or until the tops of the cookies are just cracking.
Allow the cookies to rest on the pan for a few minutes before transferring them to a wire rack to cool completely. Serve and enjoy!