My husband finished this whole batch in one night. The gooey mint center is unreal and takes 4 ingredients.

This slow cooker 4-ingredient peppermint patty cake is the kind of dessert that mysteriously disappears in one night. It bakes up into a rich, fudgy chocolate cake with a gooey, molten peppermint center that tastes like melted peppermint patties swirled through brownie batter. While peppermint patties themselves trace back to early 20th-century American candy making, this version folds that nostalgic flavor into an ultra-simple crockpot cake. With only a boxed chocolate cake mix, peppermint extract, sweetened condensed milk, and chocolate chips, it’s a practical, hands-off dessert for busy evenings, potlucks, or any time you want something decadent without hovering over the oven.

Serve this peppermint patty cake warm, straight from the slow cooker, when the white peppermint layer is still molten and the chocolate top is glossy and steamy. Spoon it into small bowls and top with a scoop of vanilla or peppermint ice cream, or a dollop of lightly sweetened whipped cream to contrast the richness. A mug of hot coffee, espresso, or black tea balances the sweetness nicely, while a glass of cold milk is perfect if you’re serving kids. For a slightly more elegant presentation, dust the top lightly with cocoa powder or crushed peppermint candies right before serving and bring the slow cooker insert directly to the table for everyone to scoop their own portion.

Servings: 8

1 box (15.25 oz) chocolate cake mix (any standard brand)

Prepare the slow cooker: Lightly coat the inside of a 5- to 6-quart slow cooker with nonstick cooking spray or a thin layer of neutral oil. This helps the cake release easily and keeps the peppermint layer from sticking to the sides.

Make the peppermint filling: In a medium bowl, whisk together the sweetened condensed milk and peppermint extract until completely smooth. The mixture should smell strongly minty; it will mellow slightly as it cooks.

Layer the chocolate chips: Sprinkle 1 cup of the semisweet chocolate chips evenly over the bottom of the greased slow cooker. These will melt into a glossy, gooey chocolate base and coating that mimics the chocolate shell of a peppermint patty.

Add the peppermint layer: Pour the peppermint-scented sweetened condensed milk mixture slowly over the chocolate chips in the slow cooker. Do not stir. You want distinct pockets of peppermint filling so it bakes into a molten, white, gooey center rather than fully blending into the chocolate.

Mix the cake batter: In a separate large bowl, prepare the chocolate cake mix according to the package directions, using the amounts of water, oil, and eggs listed on the box. Stir just until the batter is smooth and no dry streaks remain; overmixing can make the cake tough instead of fudgy.

Top with cake batter: Gently pour the cake batter over the peppermint layer in the slow cooker, covering it completely. Use a spatula to nudge the batter to the edges without pressing down too hard; you want the batter to sit on top so the peppermint filling stays mostly underneath and in the middle as it cooks.

Add remaining chocolate chips: Sprinkle the remaining 1/2 cup chocolate chips evenly over the surface of the batter. These will melt into little pools and streaks of extra chocolate on the top of the cake, adding to the rich, candy-bar effect.

Cook the cake: Cover the slow cooker with its lid and cook on HIGH for 2 to 2 1/2 hours, or until the edges of the cake are set and pulling slightly away from the sides, but the center is still soft and a bit jiggly. Avoid lifting the lid for at least the first 90 minutes; each peek releases steam and can significantly extend the cooking time.

Check for doneness: When the cake looks set around the edges, insert a knife or skewer about 1 inch in from the side. It should come out with moist crumbs and some melted chocolate, but the very center should still be gooey. The top will look like a dark, moist chocolate cake broken by glossy pools of melted chocolate and white peppermint filling, with visible steam escaping when you crack the surface.

Rest briefly and serve: Turn off the slow cooker and let the cake sit, covered, for 10 minutes to allow the bubbling to subside slightly while keeping the center molten. Serve warm by scooping down through the cake so you get layers of fudgy chocolate, gooey white peppermint center, and melted chocolate chips in each portion. Store any leftovers in the refrigerator and gently rewarm in the slow cooker or microwave before serving.

For a darker, less sweet version, use a dark chocolate or devil’s food cake mix and bittersweet chocolate chips instead of semisweet. If you want a more intense mint flavor, increase the peppermint extract to 1 1/2 teaspoons, but add it gradually and taste the sweetened condensed milk mixture as you go—peppermint can quickly become overpowering. To mimic a classic peppermint patty even more closely, swirl the peppermint condensed milk very lightly into the cake batter with a knife after pouring, leaving visible white streaks; this creates more dramatic pockets of goo when you scoop into the cake. You can also finish the cooked cake with a light sprinkle of crushed peppermint candies or candy canes for texture, especially around the holidays. For a mocha twist, stir 1 tablespoon of instant espresso powder into the prepared cake batter before pouring it over the peppermint layer; coffee underscores the chocolate flavor without making the dessert taste like coffee. If you only have a larger slow cooker, place a ring of crumpled foil around the outer edge under the insert to help buffer the heat, and start checking for doneness 15 to 20 minutes earlier to avoid overcooking the edges. Finally, for smaller households, you can halve the recipe and cook it in a 3-quart slow cooker; reduce the cooking time slightly and watch closely near the end so the center stays gooey and the top remains glossy rather than dry.