Adjust oven rack to middle position.
Heat oven to 350 degrees
Line a baking sheet with parchment paper.
Whisk, flour, baking powder, baking soda, and salt in a medium bowl; set aside.
Using a mixer beat butter, sugar and brown sugar and medium speed until just combined for about 20 seconds. Increase speed to medium and continue to beat until light and fluffy.
Add egg and vanilla and beat on medium-low until fully incorporated, about 30 seconds.
Add flour mixture about ¼ cup at a time and mix on medium to incorporate.
While mixer is running gradually add oats, and mix until incorporated for 20 seconds.
Give dough a final stir.
Using about two tablespoons of dough, roll it into balls and place 2 ½ inches apart on prepared baking sheet.
Gently press down the dough.
Bake until cookies are golden brown and edges are crispy.
About 13-16 minutes.
Transfer cookie sheets to wire rack and let cookies cool completely.