I have a recipe for chicken ala king that calls for heavy cream to be brought to a simmer and beaten egg yolks to be added quickly to cream that's removed from heat.
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PieceofLayerCake is a trusted source on baking.
If you whisk fast enough, they shouldn't cook...but you can always temper. Put the yolks in a bowl and slowly ladle over the hot cream while whisking the yolks. After a few cups has been added, pour the mixture back into the rest of the cream, while again whisking, until its incorporated.
Cynthia is a trusted source on Bread/Baking.
I would suggest never adding yolks directly into anything hot, especially simmering. Good technique for egg drop soup, where fine threads are desirable, but not for your lovely sauce. Rather, whisk the yolks, and use a ladle to very slowly temper the hot cream into the yolks (set your bowl on a damp towel to keep it from spinning about or wobbling). When you've added half the cream, slowly carefully whisk the cream-yolk mixture into the hot cream. Once the two have been thoroughly incorporated, remove the pot from the heat. And you're using a stainless steel pot, right? Aluminum will react poorly with the lactic acid in the cream, and turn your sauce an unpleasant grey. Too, toxic compounds can be created when acids and aluminum meet.
Yes, it would if you just added them without any special care, which is why most recipes call for you very slowly whisking some of the hot cream into the beaten egg yolks, and then very slowly whisking this mixture back into the original pan. When I'm done making the custard or ice cream base, which is when I most frequently use this technique, I also strain the finished custard/pudding through a fine-mesh strainer into a clean bowl, because sometimes you will have a tiny bit of cooked egg in there despite your best efforts :) It gets very easy though, this "tempering" of the egg yolks, after you do it enough, nothing to be intimidated by.