Make It Now:

1. Melt Chocolate: Melt chocolate chips in the microwave in 10-15 second intervals until smooth. Let cool for about 4-5 minutes, stirring every minute or so. If using espresso powder, combine with just enough hot water to dissolve (only a teaspoon or two) and set aside to cool.
2. Combine: Place softened butter, powdered sugar, and salt in a medium mixing bowl. Mix on medium-low speed with a hand mixer (or stand mixer using a paddle attachment) until fully combined, scraping down the sides of the bowl with a spatula as needed.
3. Whip: Add heavy cream, vanilla, and espresso mixture (optional) and beat on medium-high speed for 3-4 minutes until light and fluffy. Scrape down as needed.
4. Add Chocolate: Add cooled chocolate and mix on medium speed until fully combined, about 1-2 minutes. Use at room temperature and store in the fridge for up to a week or in the freezer for up to 3 months.

Freeze for Later: Buttercream can be frozen for up to 3 months. The easiest way to store it is to place the frosting in the middle of a sheet of plastic wrap and wrap it up to form a “pillow.” This method also allows for easy cleanup when it is removed from the freezer.

Prepare from Frozen: Remove from freezer and let buttercream thaw to room temperature. Use a stand or hand mixer and beat until light and fluffy. If the buttercream starts to separate, allow to warm up some more (continue to let sit at room temperature, torch the sides of the bowl (if metal), or heat over a gas stove or double boiler).