Preheat oven to 350°.
In a medium bowl, beat butter, sugar, salt, baking powder, vanilla, and egg. Add oats and mix. Then, mix in cashews.
Drop dough by tablespoonfuls onto lightly greased or lined baking sheets. Sprinkle each cookie with salt. Flatten cookies to about 3/8-inch thick.
Bake 12-14 minutes, or until light golden brown. Remove from the oven and cool on the baking pans.
Makes about 2 & 1/2 dozen cookies.
*I substituted sea salt to make the salt more pronounced visually.