Add the browned butter to the bowl of an electric stand mixer fitted with the paddle attachment or in a large bowl with a handheld electric mixer then add the remaining butter and let sit until fully dissolved.
After you're going to want to add your sugars and vanilla, then mix in for two minutes until completely combined. Once you've done that go ahead and add the egg and egg yolk.
Use a medium cookie scoop to portion out 1.5-2 tablespoons of cookie dough. Place the balls into an air-tight container. Chill the dough for at least an hour and a half before baking.