Quickly pulse the oats a few times in the food processor until they are light & fluffy & resemble flour.
Add flour, baking powder, table salt & cinnamon to the ground oats & stir. Set aside.
Cream the butter & both sugars together in a large mixing bowl until mixture is light & fluffy.
Slowly add in eggs, vanilla & lemon juice.
Fold in dry ingredient mixture being careful to not overmix.
Fold in chocolate chips & walnuts until just mixed throughout.
Using a cookie scoop, portion out cookie dough onto a lined tray or paper plate (something small enough to fit in the fridge).
Refrigerate scooped dough for at least 2-4hours before baking.
When ready to bake, preheat oven to 350 degrees & place chilled dough on a parchment-lined baking sheet approx. 1-2” apart.
Place the dough on your prepared baking sheet, approx. 1-2” apart.
Bake 12-14 minutes or until slightly golden brown.
Place additional chocolate chips in the tops of the baked cookies before they cool, & sprinkle the sea salt flakes over the top of all the cookies after they are baked for a bit of salty-sweet. if desired.
Cool a wire rack before transferring to an airtight container.