Preheat your oven to 325 degrees.
Line a cookie sheet with foil and lightly spray it with vegetable oil. This step is important because these cookies are delicate and can stick easily.
In a bowl, cream together the butter and sugar until combined.
Add the egg and vanilla and mix well.
Stir in the oats, flour, salt, and baking powder until everything is fully combined.
The dough will be fairly soft.
Using a 1 1/2 tablespoon cookie scoop, place dough onto the prepared cookie sheet, leaving space between each cookie because they spread quite a bit while baking.
Bake for about 9–12 minutes or until the cookies are golden around the edges and have that thin lace-like appearance.
This is the hardest part honestly… but also the most important.
Let the cookies cool completely before trying to remove them from the foil. If you try too early, they’ll stick or tear apart.
Once cooled, they peel right off and become perfectly crisp and delicate.
