Put 12 tablespoons butter into a large microwave-safe bowl. Microwave it on 50% power for 30 seconds or so, until it is very soft but not melted.
Whisk in granulated and brown sugars.
Let cool for a few minutes.
Whisk in eggs and vanilla.
In a separate bowl, whisk together flour, baking soda, baking powder, and salt.
Stir dry ingredients into the wet mixture with a sturdy wooden spoon.
Stir in white chocolate chips and nuts.
Use a 1.5 tablespoon cookie scoop to generously scoop out cookie dough and place onto lined baking sheet.
Bake for 12-14 minutes, until just starting to brown around the bottom edges.
Remove baking sheet from oven, and bang it on the counter 2-3 times.
Let cookies sit for 2 minutes, then transfer to cooling rack.
Notes
Storage Tips: Store on the counter in an airtight container at room temperature. They will last for 2-3 days, and can be heated in the microwave to soften them up a little if they get stale. You can also freeze baked cookies for up to 3 months in a freezer bag or airtight container. Bring to room temperature before serving.Expert Tips: We recommend using a cookie scoop to scoop the cookie dough—scoop generously, then roll the dough with your hands if you want to. The cookies will come out even and perfectly shaped. Also, since the cookie balls will all be the same size, you can be sure they will all bake in the same amount of time. You don’t need to bang the cookie tray on the counter, but we love how it flattens the cookies and makes them nice and chewy. Works for chocolate chip cookies too!If the cookie dough is too warm to scoop into balls, wait for it to cool, or put it in the refrigerator for a few minutes. That said, note that chilling the dough for too long will make it a lot harder to scoop.