My sister brought this to our book club and everyone demanded the recipe. The secret is letting your slow cooker do all the work

This slow cooker 4-ingredient hot chocolate fudge is exactly what my sister brought to our book club that night when everyone begged her to text the recipe before they even finished their first square. It has that rich, cozy hot chocolate flavor, with creamy fudge and swirls of melted marshmallow on top that look like you fussed for hours. The truth is, the slow cooker does all the work while you read, fold laundry, or help with homework. It’s a simple, Midwestern-style, share-with-your-neighbors kind of treat that’s perfect for holidays, snow days, or anytime you want an easy dessert that still feels a little special.

Serve the fudge cut into small squares on a parchment-lined plate or platter so the glossy top and marshmallow swirls really show. It pairs beautifully with mugs of hot chocolate, coffee, or cold milk for the kids. For a book club or game night, I like to set it out alongside a bowl of salty pretzels or roasted nuts—the sweet-salty combo keeps everyone coming back for just one more piece. You can also tuck a few squares into lunchboxes or wrap them in wax paper for quick little treats to share with friends, teachers, or neighbors.

Servings: 25–36 small squares

3 cups (about 18 oz / 510 g) semi-sweet chocolate chips

Line a square 8x8- or 9x9-inch baking pan or a small white plate with edges using parchment paper, letting the paper hang over the sides so you can lift the fudge out easily later. Set aside.

Lightly spray the inside of your slow cooker with nonstick cooking spray or rub with a little butter to help with cleanup.

Add the semi-sweet chocolate chips, sweetened condensed milk, and butter pieces to the slow cooker. Stir gently to combine everything into a rough mixture.

Cover the slow cooker with the lid and set it to LOW. Let the mixture cook for 1 1/2 to 2 hours, stirring every 30 minutes. The chocolate will look glossy and thick when it’s ready, and everything should be completely melted and smooth.

Once the mixture is fully melted and silky, turn off the slow cooker. Quickly stir in 1 cup of the mini marshmallows until they’re just starting to melt and streak through the fudge, creating a creamy, swirled look. Don’t over-stir—you want some marshmallow ribbons to stay visible.

Immediately pour or scrape the hot fudge mixture into the parchment-lined pan or plate, smoothing the top with a spatula or the back of a spoon.

Sprinkle the remaining 1 cup of mini marshmallows evenly over the top. Gently press them in just a bit so they adhere but still stay visible on the surface. If you like more swirl, use a butter knife to lightly drag through the top layer, creating soft marshmallow swirls without fully mixing them in.

Let the fudge cool at room temperature for about 1 hour, then transfer the pan to the refrigerator to chill for at least 2 more hours, or until firm enough to cut cleanly.

Once the fudge is firm, lift it out of the pan using the parchment overhang. Place it on a cutting board and use a sharp knife to cut into small squares. Wipe the knife with a warm, damp cloth between cuts for the neatest edges.

Arrange the fudge squares back onto a parchment-lined white plate or platter, marshmallow swirls facing up, and serve. Store any leftovers in an airtight container in the refrigerator for up to 1 week.

For kids who prefer things extra sweet, you can swap half of the semi-sweet chocolate chips for milk chocolate chips, which gives the fudge more of a classic hot cocoa taste. If you have dark chocolate lovers in the house, use dark chocolate chips instead of semi-sweet for a deeper, less sweet flavor. To add a hint of that café-style hot chocolate, stir in 1 teaspoon of vanilla extract right after you turn off the slow cooker, before adding the marshmallows. For a s’mores twist, sprinkle crushed graham crackers over the top along with the final cup of mini marshmallows. If you need a nutty version, you can fold in 1/2 to 1 cup of chopped toasted pecans or walnuts when you add the first cup of marshmallows. For picky eaters who don’t like the texture of marshmallows on top, melt all 2 cups into the fudge instead, or skip the topping and just smooth the surface. If you’re dairy-sensitive, look for dairy-free chocolate chips and a sweetened condensed coconut milk, and use a dairy-free buttery spread; the texture will be slightly softer but still sliceable when well chilled. Food safety tips: Keep the slow cooker on LOW only—high heat can scorch the chocolate and create hot spots. Stir carefully so you don’t splash hot chocolate mixture onto skin, and keep little helpers at a safe distance while the fudge is cooking. Always refrigerate leftovers promptly, especially in warm kitchens, to keep the fudge fresh and to prevent any dairy from spoiling. Use clean, dry utensils when cutting and serving to avoid introducing moisture, which can affect texture and storage life.