Pour honey into a small saucepan over medium heat. Heat until a thermometer inserted into the saucepan reads 240 degrees F (115 degrees C).
While honey is heating up, beat egg whites in a stand mixer fitted with the whisk attachment until stiff peaks form. Slowly and gradually pour hot honey into the egg whites, keeping the mixer on medium-high speed. Keep mixer going until the bowl cools to room temperature.
Add pieces of soft butter gradually, with the mixer still going. Add vanilla extract. Keep mixing until mixture comes together and is the consistency of buttercream, up to 10 minutes.
