Preheat oven to 350 degrees F. Line a large baking sheet with parchment paper and set aside.
Whisk together the flour, baking powder, baking soda, and salt in a medium bowl. Set aside.
Using a stand mixer, beat the butter and sugars together until creamy. Stop and scrape down the sides of the bowl as necessary. Add the eggs and vanilla, mix until combined.
Add the dry ingredients to wet ingredients. Mix on low until just combined. Don't over mix. Stir in the oats and chocolate chips.
Use a cookie scoop and drop cookies on baking sheet, about 2 inches apart.
Bake for 10 to 12 minutes or until cookies are lightly browned around the edges and still soft in the centers. Remove cookies from oven and sprinkle with flaky sea salt, if desired. Let the cookies cool on the baking sheet for 5 minutes. Transfer to a cooling rack and cool completely.
Notes
Store the cookies in an airtight container on the counter for up to 3 days. You can also freeze the baked cookies or cookie dough balls for up to 3 months.