Sift together the flours, baking powder, and salt in a medium bowl.

In a large bowl or the bowl of a stand mixer fitted with the paddle, beat the butter with the sugars just until it looks like a crumble topping. Refer to the step-by-step photos and the video for visual cues.

Mix in the eggs just until they're combined and the dough begins to look smooth.

Add the dry ingredients all at once. Mix on low just until they're incorporated. I like to do the last bit of mixing by hand with a wooden spoon or very sturdy silicone spatula, to be sure there’s no unmixed dough on the bottom, without overmixing the rest. Dough will be very stiff at this stage.

Mix in the walnuts and chocolate chips to distribute evenly. I like to do this part by hand as well, but you can use the paddle on a stand mixer if you like. It will take a bit of elbow grease either way.

Divide the dough into nine 6-ounce (170-gram) balls. Use your hands to shape them very lightly. The final result should be rough and rustic, not packed and spherical. Line two sturdy baking sheets with parchment and arrange four balls on one sheet, five on the other, leaving plenty of room in between.

Place the cookie sheets into the fridge for 30 minutes. It's important to chill the sheets as well as the dough balls.

Preheat oven to 375°F (190°C) with a rack in the center.

Transfer one cookie sheet from the fridge to the center oven rack. (You'll bake the sheets one at a time.) Bake until cookies are lightly browned on top and underneath and still very soft inside, about 18 minutes.

Let cool for at least 15 to 30 minutes before serving, right on the pan — longer if you can. This helps the cookies set perfectly.