Preheat the oven to 375°F/190°C/Gas 5. Line a large baking sheet with parchment paper or a silicone baking mat.
In a large bowl, cream together the butter, brown sugar, and granulated sugar until light and fluffy.
Beat in the eggs and vanilla extract until well combined.
In a separate bowl, whisk together oats, flour, pumpkin pie spice, baking powder, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Stir in the raisins.
Cover the dough and refrigerate for 30 minutes.
Scoop the dough into 24 equal-sized balls and place them on the prepared baking sheet, leaving space between each.
Flatten slightly with the bottom of a glass (wet the glass to prevent sticking).
Bake for 8–10 minutes, until golden brown around the edges.
Cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.
Serve and enjoy with a glass of milk or a pumpkin spice latte!