I have made the Royal Honey Buttercream twice and it is coming out too soft - what am I doing wrong? The consistency I end up with is too squishy to use between layers or to decorate with. I LOVE the flavor of this icing, so I would like to know what I can do to get it right. Do I need to let the honey boil longer? Beat the egg yolks longer?

This is a variation on the neoclassic buttercream, which is soft but still firm enough to pipe shells or stars or rosettes with as long as it doesn’t get too warm.  I don’t think you could pipe roses with it.

A few things to check:
Is the syrup bubbling thickly all over (not just a little boiling in the middle)?
You can beat the eggs for as long as five minutes on high before adding the hot syrup. 
Are you getting all the syrup into the eggs?  Scraping the pan (or measure)?
Is the egg/syrup mixture cooled to room temp before you add the butter?
Is the butter about 65-70F when you make the buttercream?

Also, after the buttercream sits for a while it softens, which is lovely to eat but doesn’t work if you’re still trying to frost/pipe with it.  It needs to be rebeaten to firm up again.

This is unrelated to the recipe as written (and might not help at all with this recipe), but if you can get raw (unheated) honey, it is much thicker—it’s about the texture of slightly soft wax at room temperature.  When it’s warm, it’s liquid and easy to mix.  Then, it will firm up and keep your frosting from being too thin.  It’s a great way to sweeten buttercream—or any frosting—without having any grittiness of sugar or powdered sugar.  Raw honey is light yellow, opaque and about the texture of sligtly soft wax, but is meltingly perfectly smooth. My favorite is Y&S.

Hi ChristaBaker, I have made this particular buttercream three times and I always let the eggs whip in the stand mixer for 10 minutes by a timer before adding my hot syrup.  I agree with everything that Julie says with this one little difference.  This is a delightful buttercream to use. Good luck!