Swiss Meringue Buttercream

8 oz egg whites
12 oz sugar
24 oz unsalted butter at room temperature
2 teaspoons vanilla extract or vanilla bean paste

In a bowl of an electric mixer, lightly whisk egg whites and sugar together over simmering water until the sugar crystals are completely dissolved and a candy thermometer reads 140F.

Place the egg-sugar syrup into mixer and whip on high with the whisk attachment until the bowl has cooled to almost room temperature (about 15 minutes). Cut up butter into tablespoon -sized pieces.

Turn mixer down to lowest setting and begin adding the butter pieces a few at a time over a minute or two until all the butter is added.  Turn mixer up to medium-low speed and incorporate all the butter for a few minutes.  Take off whisk attachment, scrape bowl and put on paddle attachment.  Continue to mix at medium high speed for another five minutes or until mixture emulsifies into a soft, smooth buttercream.

Add vanilla and mix for another few minutes until incorporated.

Variations:

Add 10 oz of melted and cooled (but still liquid) dark chocolate with vanilla at the end.

Add 8-10 oz peanut butter (according to your taste).

Add 4-6 oz Nutella (Nutella adds a lot of fat so if I add too much of it I find that my SMBC is too soft to work with).

Add 8-10 oz room temperature caramel sauce.

Add 1/2 cup honey.

Add 1 1/2 cups fresh strawberries, pureed.