1½ cups (3 sticks) butter, cool but not cold and cut into cubes
1 tablespoon vanilla bean paste
1 teaspoons vanilla extract
2 teaspoons ground cinnamon
pinch of salt
1 tablespoon plus one teaspoon bourbon (optional)
Instructions
Wipe the metal bowl of an electric stand mixer, whisk attachment and a whisk with vinegar or lemon juice and a paper towel to remove any trace of grease.
Fill a saucepan with 1 inch of water and bring to a boil, then reduce to a simmer. Place a metal mixing bowl over the pot of simmering water (bowl should fit snugly but should not touch the water) and add the egg whites and sugar. Stir constantly with a whisk until the temperature reaches 140 degrees on a candy thermometer or until all the sugar has dissolved and the mixture is foamy and the egg whites are hot. I dip a finger into the egg white then rub my fingers together to tell whether there are still grains of sugar or not. Remove from heat.
Beat egg whites and sugar on high speed with a whisk attachment until the bottom of the bowl is completely neutral, about 10 minutes. Switch to the paddle attachment and turn mixer on low speed.
Begin slowly adding the butter pieces and mix until the texture is smooth. If the buttercream curdles, keep mixing, it'll come back together.
Add the vanilla bean paste, vanilla extract, cinnamon, and a pinch of salt and mix. Add the bourbon a teaspoon at a time (there will be a total of 4 teaspoons).
You can store buttercream in the fridge in an airtight container for 3 days, or in the freezer for up to 6 weeks.
Recipe by oh honey bakes at https://ohhoneybakes.com/apple-cinnamon-cake-gf/