Start by pouring 110g of corn oil into a large bowl. Crack in 1 egg and add 100g of granulated sugar. Use a whisk or chopsticks to mix the oil, egg, and sugar thoroughly. Keep mixing until the sugar dissolves completely, and the mixture becomes smooth and delicate, with no visible sugar granules.

Sift 270g of cake flour into the bowl with the wet ingredients. Then, add 3g of baking powder and 2g of baking soda. Mix the dry ingredients into the wet ingredients with a silicone spatula until roughly combined. You'll notice the mixture will look a bit lumpy at this stage. Next, use your hands to knead the mixture into a smooth dough. Be sure to knead evenly, applying consistent pressure to ensure the dough is soft, elastic, and free of dry or hard spots.

Add 70g of chopped walnuts to the dough. Gently knead them in, making sure the walnuts are evenly distributed throughout the dough. This will ensure that every bite of the cookie has a delicious walnut crunch!

Divide the dough into 40g portions. You can adjust the size based on your preference, but for this recipe, I made 15 pieces. Roll each portion into a ball and place them on a baking tray. Gently press each ball down with your fingers and create a small indentation in the center. Sprinkle some black sesame seeds on top of each cookie

Preheat your oven to 170°C (340°F) with both top and bottom heating. Once preheated, place the tray on the middle rack of the oven and bake for 25 minutes. Keep an eye on the cookies, as oven temperatures can vary, and adjust accordingly. You'll notice the cookies expanding and turning a golden color as they bake. When the edges are slightly browned, and the surface feels crisp to the touch, the cookies are done.

Remove the tray from the oven and let the walnut cookies cool on the tray for a few minutes. After they've firmed up slightly, transfer them to a wire rack to cool completely. Once cooled, the cookies will be nice and crisp. Store them in an airtight container to keep them fresh for a few days.