A few ingredients go a long way when it comes to hot chocolate bombs, a cozy treat that has quickly gained popularity on social media. These chocolate balls may look unassuming from the outside, but when placed in a cup of warm milk, the outer shell “explodes” to reveal hot cocoa powder and marshmallows within. Once mixed together, it makes for a rich cup of hot chocolate, and a fun recipe to assemble and give as gifts to family and friends.

You’ll need a silicone mold with cavities about two-and-a-half inches wide, a pastry brush or clean paint brush to spread the chocolate, and an instant-read thermometer to help you temper the chocolate. (Silicone chocolate molds have become hard to track down, but silicone cupcake liners make a good alternative.) While tempering your chocolate isn’t necessary, it’s worth the few extra steps to ensure that the chocolate dries smooth and hard, especially if you plan to give your hot chocolate bombs as gifts.

You can, and should, customize the recipe to fit your taste. Feel free to scale up or down depending on how large of a mold you would like to use and how rich you want your hot chocolate. Decorating the hot chocolate bombs once you’ve assembled them is half the fun, though remember to stick to treats that will go well in your cup of cocoa, like holiday-themed sprinkles or crushed candy canes.

Time: About 2 hours

Yield: 6 hot chocolate bombs

12 ounces semisweet chocolate, finely chopped (1 ⅓ cups)

6 tablespoons hot cocoa mix, plus more if desired

30 to 40 mini marshmallows

Sparkling sugar, sprinkles or crushed candy canes, for decoration

1. Temper the chocolate: Melt two-thirds of the chocolate (8 ounces) in a double boiler or heatproof bowl set over a saucepan of simmering water (or microwave in a microwave-safe bowl in 15-second intervals). Stir gently as it melts and use an instant-read thermometer to ensure it doesn’t exceed 100 degrees. The chocolate should be just melted and warm to the touch. Remove from the heat and add the remaining chocolate a few pieces at a time, stirring after each addition, until melted. Continue stirring until the temperature lowers to between 88 and 91 degrees.

2. Make the chocolate shells: You will need two 6-cavity silicone molds with 2 ½-inch-diameter half spheres. Using a pastry brush or a clean paintbrush, evenly coat inside of each mold with about 1 teaspoon of melted chocolate. Repeat to make 12 half-spheres, working in batches if needed. Let the coated mold sit at room temperature until the chocolate is hard, 15 to 30 minutes. Repeat twice for three chocolate coatings total. If needed, reheat the melted chocolate to between 88 and 91 degrees between coatings by stirring over simmering water or microwaving for 15 seconds.

3. Carefully remove the hardened chocolate shells from the mold. (If you have them, wear plastic gloves to prevent fingerprints on the chocolate.) To even out the shells’ edges, warm a pan on the stove over low heat and gently press the rims of the chocolate shells onto the pan for a few seconds. Transfer the shells to your mold or a muffin tin turned upside-down to let the edges set and to balance them while you assemble the bombs.

4. To assemble a hot chocolate bomb, grab two of the chocolate shells. Put 1 tablespoon hot cocoa mix and 5 to 6 mini marshmallows in one shell. (Adjust the amount of hot cocoa mix and marshmallows you put inside your bomb depending on how rich you want your hot chocolate.) Press the rim of the empty shell onto the warm pan until the chocolate begins to melt. Gently press the melted rim against the rim of the filled shell to create a ball. To seal the ball, paint a little of the remaining melted chocolate around the seam with the paintbrush, your finger or the back of a spoon. Repeat with the remaining ingredients.

5. Drizzle any remaining melted chocolate over the hot chocolate bombs and sprinkle sparkling sugar, sprinkles, crushed candy canes or any other edible decorations on top.

6. To serve, drop a hot chocolate bomb in 8 ounces (1 cup) of very warm milk in a mug and watch the chocolate shell melt away to reveal the marshmallows and hot cocoa inside. Stir until the chocolate completely melts and enjoy.