Preheat the oven to 350 degrees F (175 degrees C). Grease two baking sheets.
Sift flour, baking powder, baking soda, and salt together in a bowl.
Cream butter, white sugar, and brown sugar in a large bowl with an electric mixer until light and fluffy. Beat in one egg at a time, then stir in vanilla. Gradually stir in flour mixture. Fold in oats and chocolate chips. Drop by rounded teaspoonfuls onto the prepared baking sheets.
Bake in batches in the preheated oven until set, 8 to 10 minutes. Allow cookies to cool on baking sheets for 5 minutes before removing to a wire rack to cool completely.
Cowboy Cookies · Dinner Match Lab | Dinner Match Lab