Place about 2/3 of butter in a skillet, melt and lightly brown the butter. Pour browned butter over cold butter in mixing bowl and mix until cold butter is melted.

Mix in sugars. Add eggs one by one, mixing well after each addition. Mix in vanilla. Mix thoroughly, then allow to sit for 3 minutes. Mix 30 seconds, then repeat twice.

Add dry ingredients and mix at low speed until just combined, 5 to 10 seconds. Drop chocolate pieces in and incorporate them without breaking them.

Cover in plastic and refrigerate for 24 to 36 hours.

Transfer sheet to a wire rack for 10 minutes, then slip cookies onto another rack to cool a bit more. Repeat with remaining dough, or reserve dough, refrigerated, for baking remaining batches the next day. Eat warm or at room temperature.