Preheat oven to 350 degrees. Lightly grease two baking sheets, or line with parchment paper.
Toss the nuts with the 1/4 teaspoon salt and spread them on a rimmed baking sheet. Bake them until they're beginning to brown, 8 minutes. Remove them from the oven and set them aside to cool.
Beat the butter, sugar, vanilla, cinnamon, 1/2 teaspoon salt and baking powder until creamy. Beat in the egg, then the oats. Stir in the chips and toasted walnuts. Drop the dough by tablespoonfuls onto the prepared baking sheets.
Bake the cookies, reversing the pans midway through (top to bottom, bottom to top), for about 20 minutes, until they're golden brown around the edges, through still quite light in the center. Remove them from the oven and transfer them to a rack to cool.
3 PPL each