Place an oven rack in the middle positions, and preheat your oven to 410 F (210 C). It should be preheated to 410 F (210 C) for at least 15 to 20 minutes before the dough is placed inside the oven.

In a large mixing bowl, sift together 1 1/2 cups of cake flour, 1 1/2 cups of AP flour, 1 tsp of cornstarch, 3/4 tsp of baking soda, and 3/4 tsp of salt. Sift these together, then whisk to combine.

Take 2 sticks (1 cup) of cold unsalted butter, and cut them into cubes. In the bowl of your stand mixer, add in the cold cubed butter, 1 packed cup of dark brown sugar, and 1/2 cup of granulated sugar. With the paddle attachment, mix them together on low-medium speed (level 3) until the mixture looks fluffy, about 2 to 3 minutes. Because of the cold butter, mixing it at a higher speed than level 3 may cause sugar and butter to fly out of the bowl.

When the sugars and butter are creamed together, stop the mixer and scrape down the sides and bottom of the bowl as needed. Turn the speed up to medium (level 4), and add in 2 large eggs, one at a time, making sure the first egg is mixed in before adding the second one. Add in 2 tsp of vanilla extract. Continue to mix until the wet ingredients are well combined.

Turn the mixer down to low speed (level 1), and slowly add in the dry ingredients. Continue mixing until just combined. Try not to overmix the dough.

Detach the bowl from the stand mixer, scrape down the bowl as needed, and fold in any unmixed dry ingredients from the sides until the mixture is uniform. And in 2 cups of semisweet chocolate chips and 2 cups of roughly chopped walnuts. Stir them in by hand until the mixture is uniform and the chocolate chips / walnuts look evenly distributed.

Note: If you have a nut allergy or prefer to have your chocolate chip cookies with no nuts, you can substitute the walnuts with dark chocolate chips (i.e. add 2 cups of dark chocolate chips instead of the walnuts). Do not omit the walnuts without adding more chocolate chips. Otherwise the ratio of solids to fat in the dough will be imbalanced, which will affect the resulting cookies.

Line 2 jelly roll pans (10.5" x 15.5") with parchment paper. Divide the dough into 8 pieces onto the parchment paper (4 balls of dough on each sheet pan) and shape them into roughly shaped balls with your hands. Take dough from the larger pieces and transfer them to the smaller pieces, till all 8 balls are around the same size. Try not to compress the dough too much while shaping. The surfaces should not be smooth, but a little rough and uneven for a more interesting texture in the final cookies.

Place both jelly roll pans on the middle rack side by side, and bake in the preheated oven at 410 F (210 C) for 10 to 12 minutes, or until the tops are golden brown.

Let them rest on the sheet pans for 5 minutes, then transfer to a metal rack to cool further. Serve warm or at room temperature. Enjoy!