Anyone know what the term is for heating and/or cooling a liquid or melted substances in stages? That’s right tempering. Where a food substance like chocolate is concerned, tempering can be a somewhat involved process (designed as it is to produce a certain type of fat crystal that gives chocolate it’s sheen and brittle “snap”). Pastry cream tempering is much simpler. The goal is to heat the egg yolks slowly and gently to prevent them from cooking into scrambled eggs. It might not seem so gentle, given that the process calls for pouring boiling milk and cream over egg yolks, but trust me it is. The actual amount of heat transfer into the yolks is much less than the opposite action would be (i.e. pouring a mixture of yolks into a pot of boiling cream), thus the yolks heat up and thicken slowly instead of coagulating into lumps.