Line a 9 by 5 loaf pan with a sheet of plastic wrap or parchment, leaving enough hanging over sides to cover. Set aside.

In a double boiler or a large bowl set over a small pot of simmering water, add your espresso, extract, large egg yolks and sweetener. Whisk until thickened, about 4-5 minutes. Stir continually to avoid scrambling yolks. Lower heat if necessary.

Test thickness by scraping bottom of the bowl with a wooden spoon. If you can see the bottom of the bowl when scraping, it's thick enough. Remove from the heat. Set aside.

Using a stand mixer or hand mixer, beat your heavy whipping cream, vanilla extract and sweetener until whipped and it holds its shape. Take a spoonful of the cream mixture and stir it into the coffee egg mixture to temper it.

With the electric mixer on low speed, drizzle in the rest of the coffee egg yolk mixture until all combined and smooth.

Stir in optional chocolate chunks if desired.

Pour this into the loaf pan then cover the top and place in the freezer for 4-6 hours or preferably overnight.

Remove from the freezer 10 minutes before you'd like to serve. Top with shaved chocolate or chocolate chips if desired. Slice and enjoy!