In a medium bowl, combine oats, flour, baking powder, baking soda and salt. Set aside.
In a large mixing bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Add granulated sugar and brown sugar. Beat on medium speed until mixture is combined, scraping sides of bowl occasionally. Beat in eggs and vanilla until combined. Beat in as much of the flour mixture as you can with the mixer. Stir in any remaining flour mixture with a wooden spoon until combined. Stir in chocolate pieces, nuts and grated chocolate.
Drop dough from a large cookie scoop (3 tablespoons) 4 inches apart onto ungreased cookie sheets. Bake in a 375 degree F oven for 9 to 10 minutes or until edges are light brown. Cool on cookie sheets 1 minute. Transfer to wire racks and let cool. Makes about 30 cookies.