Start by warming the heavy cream in the microwave for 30 - 45 seconds, or until it reaches about 115°F/45°C. Make sure that the heavy cream is not boiling, but slightly simmering. As very hot cream will result in greasy truffles.
In a large bowl, combine the warm cream, chocolate, espresso, butter, vanilla, and salt. Whisk until smooth and the ingredients are fully combined. This chocolate mixture is called "ganache". If the chocolate is not melting completely, put the heat proof bowl over a pot of simmering water. Stir until melted.
Place the ganache in the fridge to chill for 2 hours, or until it has fully set (and up to 3 days if making this recipe ahead). If the ganache is not setting, you can reheat it and add more chocolate. Then chill again. This should thicken the chocolate mixture.
Once the chocolate has set, use a cookie scoop to scoop balls onto sheet pans lined with silicone liners or parchment paper. Smooth the truffles by rolling them using your palms to shape even balls. They will be sticky at this moment, and that's ok.
Place the truffles in the freezer to chill for 10 minutes.
Add the chopped chocolate and coconut oil to a medium bowl. Microwave it on 30 seconds intervals. Stirring the mixture between each interval until fully melted and ingredients are combined.
Dip each truffle one at a time into the melted chocolate using this dipping tool or a teaspoon. Gently, tap with the dipping tool on the side of the bowl to get rid of excess chocolate. Then place it on sheet pans lined with silicone liners or parchment paper.
While the chocolate is still wet, add any sprinkles or decoration (optional). The truffles in this recipe are topped with sea salt and a drizzle of chocolate. You'll find more options for topping in the following section below.
Allow the chocolate to set fully and enjoy!
Notes
Chocolate - Any kind of chocolate can be used in this recipe. Dark and milk chocolate are delicious options. Avoid using white chocolate as it's too thin.
Coating - You can use chopped chocolate and shortening (such as coconut oil) to dip truffles in, as recommended in this recipe. Alternatively, you can buy dark, white or milk chocolate confectionery coating from the grocery store. This coating is sometimes labelled as "candy coating" or "almond bark". If using candy coating, there's no need to add shortening.
Boozy truffles - To make boozy truffles, substitute the espresso for Kahlúa.
Salt - You can replace sea salt with ¼ teaspoon of kosher salt.
Topping - suggestions of toppings are: Crushed candy cane pieces, crushed pistachios, walnuts, nuts or cashews, toasted chopped pecans, shredded coconut, toffee bits, cocoa powder, Oreo crumbs, sea salt, crushed banana chips, graham cracker crumbs or sprinkles.
Double boiler - if you don't want to use the microwave, you can use the double boiler over a low simmer instead.