Brown the butter using one of the methods below:Stovetop: Melt butter over medium heat. It will foam, then bubble. Once brown flecks appear and it smells nutty, remove from heat.Toaster Oven: Place butter in an oven-safe dish and bake at 350°F for 10–15 minutes. Watch closely until bubbly with brown flecks.Let the butter cool for at least 30 minutes, until no longer hot.
Mix Butter and Sugars
Add the cooled browned butter and both sugars to a large bowl. Beat with an electric mixer until combined.The mixture will look slightly dry and crumbly, like wet sand.
Add Egg Yolks
Add the egg yolks and beat for 2–3 minutes.The mixture will become lighter in color and fluffier in texture.
Add Sourdough Discard
Add the sourdough discard and mix with a spoon or spatula until combined.The mixture will look more like a thick batter at this stage.
Add Remaining Ingredients
Mix in: salt, baking soda, baking powder, and vanillaThen add: flour and chocolate chipsMix until fully combined and there are no dry spots of flour.
Chill the Dough
Cover the dough and refrigerate overnight.This step improves flavor, texture, and fermentation.
Preheat and Prepare
Preheat oven to 350°F.Line a baking sheet with parchment paper.
Shape the Cookies
Scoop dough into balls and flatten slightly into a hockey puck shape (about 1/2 inch thick and 2–3 inches wide).Place on baking sheet, leaving space between cookies.
Bake
Bake for 12 minutes.Rotate the pan, then bake for an additional 6 minutes.(If your oven bakes evenly, rotating is optional.)You want them to be nice and golden brown around the edges.
Cool and Enjoy
Remove from oven and let cookies cool on the pan before serving.
Notes
Browning the butter adds a deep, nutty flavor that makes these cookies extra rich.
Chilling the dough overnight is highly recommended for best texture and flavor.
Cookies may look slightly underdone when removed from the oven—they will continue to set as they cool.