1) Preheat your oven to 375°F. Lightly grease (or line with parchment) four baking sheets, or as many as you have.
2) Beat together the butter, sugars, baking powder, baking soda, and salt.
3) Beat in the eggs and vanilla.
4) Using a blender or food processor, process the oats with the white chocolate until the oats are finely ground, and the chocolate is mostly ground; a few small chunks are OK.
5) Add the oats and flour to the butter mixture, then stir in the peanut butter chips, chocolate chips, and chopped walnuts.
6) Drop the dough by tablespoonfuls, 2" apart, onto the prepared baking sheets.
7) Bake the cookies for about 12 minutes, until they're just set. They may be barely starting to brown around the edges, but the tops won't be brown at all.
8) Remove the cookies from the oven, and cool.
Yield: 5 dozen cookies.