Combine granulated sugar and eggs in a large bowl or the bowl of a stand mixer fitted with the whisk attachment. Beat on high speed until light in color and the volume has doubled, about 3 minutes. Using a flexible spatula, fold in the cooled chocolate mixture, then the flour mixture. Fold in the remaining 1 cup chocolate chips, being careful not to overmix. Refrigerate for at least 1 hour and up to 4 days.