Before starting, ensure the mixing bowl used is completlelyclean. Use lemon juice to wipe around the bowl to remve any grease from the bowl.
Place the mixing bowl on a pan of simmering water (ban-Marie style). Make sure the water does not touch the bottom of the bowl.
Add in egg whites and sugar and gently whisk (it doesn't have to be vigorous). Heat and mix until the temperature reaches between 68°c -71°C (155°F - 160°F.
Remove from the heat and begin whisking on a medium-high setting. The meringue should begin forming into stiff peaks and appear thick and glossy. Allow the mixture to reach room temperature.
Gradually add in the butter a few cubes at a time. Make sure each butter part is fully incorporated before adding the next. Ideally use the paddle attachment of a stand mixer for this.
Next add in the salt, rose water and lemon essence. Make sure all is fully mixed in.
[Optional] Add in food colouring to colour the buttercream. Ideally use gel colouring, as this incorporates better; however regular food colouring can still be used.
Use buttercream to frost the cake. It can also be stored in the fridge, ensuring it is in an airtight container. Return the buttercream to room temperature and mix a little before using.The buttercream can also be frozen, again in an airtight container. Defrost and return to room temperature, re-mixing before use.
Notes
Recipe originally by The Flavour Bender and can be found here: https://www.theflavorbender.com/naked-raspberry-cake-with-pistachio-and-rose-water-swiss-meringue-buttercream/
Keyword rose buttercream, Swiss Meringue Buttercream