Prep oats by pulsing old-fashioned oats in a food processor until finely ground and whole oats mixture, about 20-25 seconds.

Mix dry ingredients by whisking together all-purpose flour, pulsed oats, malted milk powder, baking soda, and salt in a medium bowl.

Cream butter and sugars: Combine unsalted butter, creamy peanut butter, light brown sugar, and granulated sugar in a stand mixer. Beat on medium speed for 3-5 minutes until light and fluffy.

Incorporate wet ingredients: Add the egg and vanilla extract to the mixture and mix on low speed until fully combined.

Blend dry into wet by gradually adding dry ingredients to wet mixture in stand mixer. Mix until just combined, about 1-2 minutes.

Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.

Using a #50 cookie scoop, portion out the dough on the baking sheet, making sure they are two inches apart.

Bake for 9-11 minutes until slightly browned edges and moist centers.

Cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely.