Step 3: Allow the Milk to Thicken and Temper the Egg Add the 2 1/2 cups of milk to the pot and stir until thick. Once thickened, lower heat. Take about 1/4 a cup of the hot milk mixture, and while whisking, slowly add it to the egg in a bowl. You want to do it gradually so you don't scramble or cook the egg. Image Sources: Instagram user gigihadid and POPSUGAR Photography / Kalea Martin