1In a medium bowl, whisk together flour, baking powder, baking soda, and cornstarch. Set aside.
2In a medium bowl, whisk together flour, baking powder, baking soda, and cornstarch. Set aside.
3In a medium bowl, whisk together flour, baking powder, baking soda, and cornstarch. Set aside.
4In a large bowl, cream together brown sugar, granulated sugar, and butter until light and fluffy.
5In a large bowl, cream together brown sugar, granulated sugar, and butter until light and fluffy.
6In a large bowl, cream together brown sugar, granulated sugar, and butter until light and fluffy.
7Beat in eggs one at a time, followed by vanilla extract. Beat for 3-4 minutes until pale and sugar is well incorporated.
8Beat in eggs one at a time, followed by vanilla extract. Beat for 3-4 minutes until pale and sugar is well incorporated.
9Beat in eggs one at a time, followed by vanilla extract. Beat for 3-4 minutes until pale and sugar is well incorporated.
10Gradually mix in the dry ingredients until just combined, being careful not to overmix.
11Gradually mix in the dry ingredients until just combined, being careful not to overmix.
12Gradually mix in the dry ingredients until just combined, being careful not to overmix.
13Stir in chocolate chips and walnuts.
14Stir in chocolate chips and walnuts.
15Stir in chocolate chips and walnuts.
16Scoop 2 tablespoon-sized balls of dough onto the prepared baking sheet, leaving about 4 inches of space between each cookie. Top it with more chocolate chips and walnuts.
17Scoop 2 tablespoon-sized balls of dough onto the prepared baking sheet, leaving about 4 inches of space between each cookie. Top it with more chocolate chips and walnuts.
18Scoop 2 tablespoon-sized balls of dough onto the prepared baking sheet, leaving about 4 inches of space between each cookie. Top it with more chocolate chips and walnuts.
19Bake at 350°F (180°C) for 13-16 minutes, or until edges are lightly golden brown.
20Bake at 350°F (180°C) for 13-16 minutes, or until edges are lightly golden brown.
21Bake at 350°F (180°C) for 13-16 minutes, or until edges are lightly golden brown.
22Remove from oven and let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.
23Remove from oven and let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.
24Remove from oven and let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.