In a large bowl, whisk together egg
yolks and granulated sugar
. Add flour
and mix until smooth. In a small saucepan, bring milk
to a boil. Whisk milk
mixture and then pour the whole mixture back into the saucepan. Return the saucepan to the heat and stir with a wooden spoon until smooth and thickened. Remove from the heat, transfer to a clean bowl, and press a piece of plastic wrap directly onto the surface to prevent a skin from forming. Let cool
completely before using.