Combine the chocolate chips and room-temperature sweetened condensed milk in a microwave-safe bowl. Heat at 70% power for 1 minute, then stir well to break up the chocolate. Continue heating in 30-second bursts, stirring between each burst, until the chocolate is completely melted and fully incorporated with the milk to create a smooth, homogeneous mixture. I find that microwave melting at reduced power prevents the chocolate from seizing or becoming grainy, which is crucial for smooth truffles.

Stir the vanilla extract into the melted chocolate mixture from Step 1 until fully combined. If you're using the optional espresso powder, sift it in and stir well to distribute evenly throughout the mixture—this will deepen the chocolate flavor without making the truffles taste like coffee. Cover the bowl with plastic wrap or foil and refrigerate for at least 2 hours until the mixture is firm enough to scoop but still soft enough to roll. A helpful tip: I chill the mixture overnight when I have time, as it becomes easier to handle and creates a creamier interior.

While the mixture chills or when you're ready to shape, arrange your toppings on separate small plates or shallow bowls. Use Dutch-processed cocoa powder as your base coating, and add any optional toppings like chocolate sprinkles or cacao nibs to additional plates. Once the chocolate mixture is firm, use a melon baller, small cookie scoop, or two spoons to form 1-inch balls of the chilled mixture, working quickly so the mixture doesn't soften too much. If the mixture becomes too soft, return it to the refrigerator for 15 minutes.

Working with one or two scoops at a time, gently roll each truffle in your chosen coating, using your palms or a small spoon to ensure even coverage. Start with the cocoa powder as it's the most forgiving base coating, then transition to any combination of sprinkles or cacao nibs for texture variety. Place finished truffles on a parchment-lined plate or container as you go. For the best texture, I like to do a light cocoa coating first, then immediately roll any remaining truffles in a second topping while they're still slightly sticky.