Add 1 1/4 cups granulated sugar to the bowl of eggs. Beat with the whisk attachment on high speed until thick and doubled in volume, about 6 minutes. The mixture should fall back on itself in a ribbon and be pale yellow in color. Reduce the mixer speed to low and pour in the milk mixture in a steady stream. Add the flour mixture, a few spoonfuls at a time, and beat, scraping down the sides of the bowl halfway through, until just combined, about 30 seconds total.
