01 -
Using a stand mixer or hand mixer, beat the softened unsalted butter with packed light brown sugar and granulated sugar for 2 minutes until pale and fluffy.
02 -
Add the large egg and pure vanilla extract, blending for 1 minute until fully incorporated.
03 -
Sprinkle in all-purpose flour, cornstarch, baking powder, baking soda, and salt. Mix on medium speed until a thick dough forms.
04 -
Gently fold the semi-sweet chocolate chips and walnut pieces into the dough until evenly distributed.
05 -
Refrigerate the cookie dough for 30 minutes to allow it to firm up.
06 -
Meanwhile, preheat oven to 475°F and line a baking sheet with parchment paper.
07 -
Portion out 2 heaping tablespoons of dough per cookie. Roll each portion into a ball and arrange them 2 inches apart on the prepared baking sheet.
08 -
Bake for 7–8 minutes until cookies are lightly golden on the edges but remain gooey in the center.
09 -
Allow cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to finish cooling. Serve warm for optimal gooey texture.