These are big, thick Chocolate Chip Cookies that have a thick golden crust and soft gooey insides like ones you'd get at a bakery in New York City. They bake up nice and tall and are so satisfying to eat, especially with a cup of coffee.
Combine flour, baking powder, baking soda and salt in a medium bowl and whisk to blend evenly.
Combine soft butter with both sugars and vanilla extract in a large bowl or the bowl of a stand mixer. Mix by hand using the "creaming method" with a wide rubber spatula to smear the butter and sugar together and mix vigorously until smooth, pale and fluffy. You can also use a handheld mixer. If you use a stand mixer, secure the paddle attachment and mix on medium speed for 2 minutes. Add the egg and mix until well incorporated.
Add the flour mixture to the butter mixture all at once and fold it in. Add chocolate chips and chopped walnuts and fold them in until evenly distributed.
Use a 2-oz cookie scoop to portion dough so you get 4 oz portions. You will need two scoops per cookie. Press two portions together and roll them up into a rough ball. You should get 6 cookies out of this dough. Alternatively you can divide the dough into 6 portions. Place them onto prepared baking sheets spacing them 3 inches apart and bake for 3 minutes, then reduce oven to 350°F and bake for another 10-12 minutes until deeply golden all over and still slightly soft in the middle.
Transfer baking tray to a rack and let cool for 3 minutes before transferring to the rack to finish cooling.